Category Archives: Common Mistakes

Common Grammar Goofs

Common Grammar Goofs

Lists like the following have been floating around high school and college classrooms, as well as workplaces, for years. They are believed to have begun in the 1970s, when George Trigg and William Safire each published their own lists. Trigg’s list can be found in Physics Review Letters, 19 March 1979 (Volume 42, Issue 12, pp. 747-748); Safire’s, called “Fumblerules,” originally came out in his “On Language” column in the New York Times, on 7 October 1979.

With apologies (or perhaps a tip of my hat) to Messrs. Safire and Trigg, I’ve reprised some of their classic examples below, with proper examples and explanations, where applicable, of how each sentence should be written immediately underneath. Enjoy!

  1. Verbs HAS to agree with their subjects.

    Verbs HAVE to agree with their subjects. (Has is third-person singular [verb has]; have is third-person plural [verbs

  2. Prepositions are not words to end sentences with.

    Prepositions are not words with which one should end sentences. (Prepositions are linking words; therefore, it is inappropriate for them to stand alone at the end of a sentence).

  3. And don’t start a sentence with a conjunction.

    Don’t start a sentence with a conjunction. (Similarly, conjunctions are linking words. It is inappropriate for them to stand alone at the beginning or end of a sentence).

  4. It is wrong to ever split an infinitive.

    It is wrong to split an infinitive. (Infinitive verbs are always preceded by the word ‘to,’ and it is improper grammar to put other words between the two words).

  5. Avoid clichés like the plague. (They’re old hat).

    Avoid clichés. (The same goes for buzzword and jargon overload).

  6. Also, always avoid annoying alliteration.

    There is no reason to run together several words that begin with the same letter. Use a thesaurus to find alternate words in order to get around this problem.

  7. Parenthetical remarks (however relevant) are (usually) unnecessary.

    Parenthetical remarks are unnecessary. They generally over-explain a point that has already been made.

  8. Also too, never, ever use repetitive redundancies.

    Finally, never use redundancies. (Redundancies are saying the same thing twice. In the example sentence, there are three pairs of redundancies: also and too; never and ever; and repetitive and redundancies).

Plagiarism: What is it, what does it look like, and how to avoid it?


Perhaps the most serious crime (yes, crime) a student or researcher can commit is that of plagiarism. Plagiarism is the act of copying another person’s words and passing them off as if they are your own. It bears repeating: PLAGIARISM IS A CRIME in academia. Although it won’t earn you a jail sentence, if you are found guilty of plagiarism, the consequences can be severe. If you are a student, plagiarism can cause you to be expelled from school. If you are a researcher or professor, plagiarism can cost you your career.

Therefore, it is important to know how to avoid plagiarism. Editors see examples of plagiarism on a regular basis; sometimes, students do not realize they are plagiarizing. The most common cause of plagiarism seems to be a failure to cite properly, whether due to unfamiliarity with how to cite direct quotations and ideas or simple oversight; the second-most common cause (again, based on my observations) seems to come from the student’s lack of confidence in his or her own ability to write. In the remainder of this blog post, I will address both of these causes and explain how easy it is for one to be caught plagiarizing.

  • Example 1: Improper citation of a direct quote:
    Let’s say you’re a special ed major, and are writing a paper on social skills for people with autism. A currently popular book on this subject is Unwritten Rules of Social Relationships, which happens to be written by two people who are on the autism spectrum.

    You write the following:

    People with various forms of autism view the world much differently than people without autism. This perspective is inborn, is due to how their brains are ‘wired,’ and is true no matter where on the autism spectrum the person lies. According to Grandin and Barron, the mind of a person with autism is one of absolutes, of thinking patterns that are rigid and repetitive, where minute details become focal points of obsessive attention, and self-involvement takes precedence over exploration.

    The plagiarism starts in line 4 of the above paragraph, with “is one of absolutes…” I will now show you how to properly cite this in APA and MLA formats.

    APA: People with various forms of autism view the world much differently than people without autism. This perspective is inborn, is due to how their brains are ‘wired,’ and is true no matter where on the autism spectrum the person lies. According to Grandin and Barron (2005), the mind of a person with autism “is one of absolutes, of thinking patterns that are rigid and repetitive, where minute details become focal points of obsessive attention, and self-involvement takes precedence over exploration” (p. 83).

    MLA: People with various forms of autism view the world much differently than people without autism. This perspective is inborn, is due to how their brains are ‘wired,’ and is true no matter where on the autism spectrum the person lies. According to Grandin and Barron, the mind of a person with autism “is one of absolutes, of thinking patterns that are rigid and repetitive, where minute details become focal points of obsessive attention, and self-involvement takes precedence over exploration” (Grandin and Barron 83).

    Note that, in both examples, the actual copied text is enclosed in quotation marks, and that the period that ends the sentence comes after the citation.

  • Example 2: Improper citation of someone else’s idea

    In another spot in your paper on social skills, you note the following:

    In people with autism, social functioning is often so impaired that what is inherent to, or can be learned through observation by, those without autism (“neurotypicals”) can only be learned through direct experience.

    This, too, is plagiarism because it’s not a commonly known fact. It’s a rephrasing, in your own words, from Unwritten Rules of Social Relationships. In APA, you don’t need a page number because there is no direct quotation; however, in MLA, you do need a page number because every MLA citation requires a page number. See below for citation examples.

    APA: In people with autism, social functioning is often so impaired that what is inherent to, or can be learned through observation by, those without autism (“neurotypicals”) can only be learned through direct experience (Grandin & Barron, 2005).

    MLA: In people with autism, social functioning is often so impaired that what is inherent to, or can be learned through observation by, those without autism (“neurotypicals”) can only be learned through direct experience (Grandin & Barron 32).

  • Example 3: Possible lack of confidence in writing skills

    This type of plagiarism takes place when large sections, if not all, of a paper are copied straight from a source. This is easy to spot when a large segment of a paper is clearly in a different writing style/fluency from the rest of the paper. I prefer to give people the benefit of the doubt, and assume they are doing it either because they don’t know it’s wrong or because they don’t have confidence in their own writing abilities, but deliberate plagiarism can and does happen. I wish to reiterate that plagiarism is often used as grounds for expulsion, as well as termination and loss of professional licenses.

    Returning to the special ed paper on people with autism, you’ve spent several pages discussing common ways to help people with autism learn social skills; now it is now time for the conclusion. The paragraph prior to the conclusion might say something like this (spelling and grammar errors are intentional):

    Even though people with autism arent born perceiving the world the way people without autism do. And though they lack social skills that most people are born with, it is greatly importance to teach them these skills so they can relate to others.

    Then, suddenly, the conclusion switches to this perfect text:


    We have to look at the physical biomedical/biochemical workings of the person, assess their sensory issues, determine whether they think from a logical or emotional framework, and then create programs that take into consideration all of these factors if we’re going to teach social functioning skills and emotional relatedness to people with ASD. Yet, many programs with a social or behavioral basis teach good/bad behavior and expect behavior conditioning to produce social understanding. That’s exactly the stage where much of our programming sits now with people with ASD – a piecemeal, compartmentalized approach to treatment.

    If there’s a basic physiological reason that social awareness is not developing in a child – their brain wires are not connected – no matter how many ways parents or professionals try to teach the child, success will be limited by that physical impairment. If his sensory systems are going haywire all the time, or stress and anxiety levels are pervasive, until those issues are addressed and alleviated, forget trying to teach more advanced aspects of behavior and sociability. Equally ineffective are mismatched teaching methods, such as appealing to the logical-minded child through emotional reasoning, or vice versa. Until we address the whole child in our teaching – whether we’re teaching language or social skills or play skills – we’re doing disservice to the child or adult. We’re expecting a lot of effort from the child, but setting him up for limited success right from the start. It all comes back to appreciating the different ways that people with ASD think.

    While the text in the conclusion sounds great and may say exactly what you were trying to, it is, nevertheless, plagiarized (taken directly from pages 92 and 93 of The Unwritten Rules of Social Relationships). There is no way around this, no way to pass this off. Rewriting or spinning this is just as unacceptable as leaving it as is, and just inserting quotes and a citation is inappropriate because of the length of the passage. Every bit of your paper, except SHORT quotations, as in example 1, must be in your own writing; when an idea is explained that is someone else’s idea, it must also be cited, as in example 2. This entire conclusion must be deleted and a new one written in your own words.

Finding plagiarism (and ways to double check yourself):

Plagiarism is easy to find; the most basic way is to Google passages from the paper. If the passage comes up verbatim in the search results… you have been caught! (For instance, I Googled just a few words of the passage in the example above; the first search result returned was here: Google Result).

There are more sophisticated ways to do it, however, on sites such as The Plagiarism Checker and Copyscape. It is likely that your professors use one or more of these more sophisticated tools.
In conclusion, plagiarism is never worth it. Be aware of what it is, and be scrupulous about making sure you never commit it.

Ensuring Consistency in Your Writing


Before submitting or distributing your essay, research report, email, or any other document, besides performing the usual spell checking and proofreading, you should make certain that your writing is consistent in terms of spellings, usages, and formatting. This is important for two reasons: it helps to guarantee the clarity of your message and it lends an appearance of professionalism to your document.

If, for example, you refer to “theatres” in one part of your paper, you should not use “theaters” in another section. Neither should you vary from “U.S.A.” to “USA” or from “Prof.” to “Professor.” This also applies to names. For example, be careful to spell “Thompson” the same way throughout your paper, and not as “Thomson” and “Tompson.”

You should also make sure you are consistent in reference to your use of numerals and letters in lists. If you use a numbered or lettered list in one section of your paper, maintain that usage later on. You must also be consistent in reference to your use of capital and lower case letters in titles and lists and headings. For example, you may decide to use all capitals in headings and titles, except for articles and prepositions (assuming this is in accordance with the formatting style you are using), as in the following: Some of the Causes of the Civil War. Therefore, similar subsequent headings should be written according to that style. And so, the following would be incorrect: Early battles during the first months of the war.

Consistency applies to spacing and paragraphing too. You should use the same number of spaces between sentences. The common practice is to insert one space between sentences, but two is also acceptable. Of course, if you use block formatting (where all lines of text end at the right margin), then the spaces between sentences (and between words) will vary.

In addition, you should make sure that all of your paragraphs begin in the same formatting manner: that is indented or left justified, and not a mixture of both styles.

Consistency applies to citations and references lists. Do not vary between MLA, APA, Chicago, and other formatting styles. Choose one, and use only that one.

In short, to ensure that your written work represents your best efforts, you must maintain consistency at all times.

APA Refresher


Reference List:

  1. Double space the reference list, but do not add any additional space between entries
  2. Be sure to place a comma between the journal title and volume number, e.g., Psychology Today, 17
  3. Be sure to place a comma between the date of retrieval and “from” when listing a source Web site or an electronic database, e.g., “Retrieved October 4, 2008, from…”
  4. Do not capitalize all major words in book titles or article titles, only in journal titles, e.g., Social adaptive theory. Psychology Today, 17
  5. Do not add a space between the volume number and the parentheses containing the issue number, e.g., Psychology Today, 17(1)
  6. Put spaces between initials, e.g., Georgia, J. M.
  7. When using a month in the date, do not abbreviate, e.g., (2005, November)
  8. Always italicize the names of documents retrieved from the Internet unless they are newspaper/journal articles, e.g., Barclay, L. (2002). The paradox of “justice”

  9. formalization: When procedures erode perceptions of fairness. Retrieved December 9, 2005, from
  10. Always place commas between the author’s name and the ampersand, e.g., Michael, J. K., & Lorne, P. J. and Georgia, B. K., Mason, H. G., & Teakes, M. N.

In-Text Citations:

  1. (when using “et al.”) do not place a comma after the author’s name and be sure to place a period after “al,” e.g., Georgia et al.
  2. Place a comma between the author’s name and the year, e.g., (Terwilliger & Simpson, 2008)
  3. Use ampersands, e.g., (Terwilliger & Simpson, 2008, p. 3)
  4. Be sure to place a space between “p.” and the page number, e.g., (Georgia, 2003, p. 22)
  5. Use serial commas, e.g., (Mason, Georgia, & Lenny, 2008)


  1. When using a running head, be sure it is formatted as follows: Running head: INDIVIDUAL DIFFERENCES IN BIMODAL PROCESSES
  2. Do not label the introduction
  3. Repeat the title on the first page of the document text
  4. Do not use underlining or bold for headings

Capitalization, Abbreviations, and Percentages:

  1. Spell out United States when used as a noun
  2. Do not capitalize the names of theories, excepting, of course, proper names within them, e.g., social adaptive theory and Darwin’s theory of evolution
  3. In general, capitalize sparingly
  4. Percents are always given as numbers plus the percent sign, e.g., 25%

Varying Your Vocabulary


Many words in the English language have synonyms. Using them in written material allows documents to sound more interesting by virtue of the fact that it helps the writer to avoid what might sound like repetitious phrases. In addition, some synonyms are more precise and have a more professional/academic sound to them than other words which have similar meanings. Rather than writing, for example, I am going to try to get better grades in school, you might write, I am going to attempt to achieve better grades in school.

Here is a short list of common words, and some of their synonyms:

  • get……..obtain, acquire, acquire…
  • try……..attempt, endeavor, strive…
  • make….create, compose, develop…
  • find……discover, locate, uncover….
  • take……obtain, receive, procure…..
  • do………perform, accomplish, achieve
  • put……, situate, deposit
  • give…….offer, present, furnish
  • idea…….thought, concept, inspiration

Obviously, this is a very small sample of the thousands of words that are commonly used and their synonyms.

Here’s a hint: when you have written a word in a document for a second or third time, use the Microsoft Word Thesaurus to find a synonym. Doing so will allow your written piece to appear to be fresher and more interesting than it would if you were to use the same words repeatedly.

Writing about Writing


Which tense should be used when writing about published content, whether fiction or non-fiction? Should descriptions of characters, scenes, concepts, and themes be written in the present or past tense?

In reference to works of fiction, some may feel comfortable writing, Mark Twain’s character, Huck Finn, was a young boy who travelled the Mississippi River on a raft with a runaway slave named Jim. Others may prefer Mark Twain’s character, Huck Finn, is a young boy who travels the Mississippi River on a raft with a runaway slave named Jim. Both are correct. However, since works of fiction, especially classics, are considered enduring (that is, the characters, scenes, etc. survive), it is preferable to write about them in the present.

This is true of works of fiction that are centuries old, such as The Canterbury Tales, and novels and other fictional works that are on today’s bestseller lists. Therefore, when writing about, for example, Charles Frazier’s Cold Mountain, it is preferable to write Inman climbs out of his hospital bed, and starts for home, rather than Inman climbed out his hospital bed and started for home.

There may be times when you are confronted with the question of how to write about an event in a book which occurred before the timeline of the scene that is being described. For example, in one section of Harper Lee’s To Kill a Mockingbird, the narrator, Scout, remembers that her father “had served for years in the state legislature.” When writing about that scene, it would be correct to write in the present tense, except for the part which relates to the past event: At this point, Scout thinks about how her father had served in the state legislature for years.

Of course, when you quote dialogue or narration directly from a book, it must be exact. That includes the tense that the author used, which, in fiction, is generally past, as in the following from Lord of the Flies by William Golding: “And an airplane, and a TV set,” said Ralph sourly, “and a steam engine.”

When writing about non-fiction works, whether they are books, newspaper, magazine, or Internet articles, scholarly papers, etc., it is still appropriate to use the present tense. For example, when describing the building of the Panama Canal in David McCullough’s The Path Between the Seas, it is correct to write, McCullough describes the harshness of the Panama rainforest in great detail. On the other hand, when writing about a specific scene or event, since the book is a work of history, and, thus, describes real events which already occurred, the past tense would be correct: Many in Congress were against constructing a sea level canal through the Isthmus of Panama.

Dos and Don’ts List #1


Abbreviation: United States

  • The abbreviation requires periods except in scientific text
  • Abbreviate when using it as an adjective, e.g., U.S. currency or U.S. involvement in international politics
  • Spell out when used as a noun, e.g., the United States was established in 1776, but it was not recognized as such until 1783

Clauses of attribution (e.g., Smith states, “…”)

  • Capitalize the first word of a quotation following such a clause
  • Do not use “that” with such clauses, e.g., use Smith states, “…” rather than Smith states that “…”

Word Choice

  • YES homemaker NO housewife
  • Yes inexpensive/less expensive NO cheap/cheaper
  • YES state, exclaim, assert, share, declare, and maintain NO say


  • Only capitalize president and other titles when they precede a name, e.g., President Lincoln
  • (when referring to the western part of the world or the United States) YES the West and Western NO the west and western
  • YES Internet NO internet


  • (before a noun) YES middle-class (acting as a noun) YES middle class
  • YES user-friendly (always, not just before a noun)
  • YES hardworking NO hard-working
  • (before a noun) YES problem-solving (acting as a noun) YES problem solving

One word or two?

  • YES data set NO dataset
  • YES Web site NO website or Website


  • Separate e.g. and i.e. from any sentence they are in using commas on both sides, for example, singers, e.g., Mariah Carey and Madonna
  • or put them in parentheses and use a comma on the right, for example, singers (e.g., Mariah Carey and Madonna)

British English

  • Verbs and nouns spelled with a z in American English are replaced with an s in British English, e.g., analyze (analyse), recognize (recognise), and organization (organisation). I usually use the Word find function to search for zs when working with British English because the spellchecker misses quite a few.
  • Use towards in British English and toward in American English

Apostrophes and Quotation Marks: When to Use Them


When it comes to punctuation, the two most common kinds of errors involve the use of apostrophes and quotation marks. The rules governing the use of apostrophes and quotation marks are, for the most part, clear and unyielding.

Let us review apostrophes first. They are used for two purposes: to show possession and for contractions.

To show possession of something or someone by a singular noun, an apostrophe followed by an “s” is used, as in the following examples:

  • The doctor’s office was crowded.
  • My younger son’s friends are coming for dinner tonight.
  • Where is Marty’s coat?
  • That is the girl’s necklace.
  • This is Charles’s coat. (Notice that, even though “Charles” ends in an “s,” it is still necessary to add an apostrophe and another “s.”)

The only time that you would add just an apostrophe to the end of a noun ending in “s” would be if adding an apostrophe and an “s” would change the pronunciation of the word, as in the following:

  • We have discussed Sophocles’ body of work.

It should not be “Sophocles’s work.” That would change the pronunciation of “Sophocles.”

When you are indicating possession by plural nouns, just an apostrophe is added, as in the following examples:

  • All of the girls’ mothers came to the reception.
  • That building contains several doctors’ offices.

Irregular plural nouns require the addition of an apostrophe and an “s,” as in the following:

  • That is the children’s room.
  • He decided to join the men’s club.

Contractions are formed by combining two words. Apostrophes are added in place of letters which have been dropped, as in the following examples:

  • should not……shouldn’t
  • could not……..couldn’t
  • she will…………she’ll
  • it is……………….it’s (This should not be confused with the possessive form of “it,” which is “its” (no apostrophe).
  • you are…………you’re
  • cannot (always written as one word)…….can’t

Quotation marks are correctly used only to indicate the actual words that someone has said or written or sung, around the titles of certain created works, and to set off unique phrases.

To indicate speech:
The following are examples of quotation marks being used to indicate the actual words of a speaker or those in a written work or a song:

  • “My brother has been gone all day,” Ken said.
  • “Do you know where he could possibly be?” asked Ralph.
  • “Well,” Ken replied, “he could be anywhere.”
  • I am always thrilled when I hear the phrase “the land of the free and the home of the brave.”

The titles of newspaper, magazine articles, or periodical articles, the titles of short stories, plays, films, musical pieces, poems, essays, and television and radio programs should be enclosed in quotation marks.

Unique phrases or irony:
Quotation marks may be used to indicate that a word or phrase is unique and should, therefore, be set apart from the rest of a sentence, as in the following:

  • Tom decided that he did not want to be part of “the moral majority.”

Here is an example of quotation marks being used to indicate irony:

  • Well, I am going to show my boss just how “irresponsible” I can be.

More often than not, errors involving the use of apostrophes and quotation marks have to do with their overuse. They should not be used to emphasize important phrases. The following is an example of that:

  • Everyone is invited to the “Big Sale.”

As stated above, the rules involving the use of apostrophes and quotation marks are clear. Learning how to use them involves simply studying the rules.

Learning How to Write by Reading


One of the best ways by which to learn how to write properly is to read—almost anything, novels, non-fiction books, newspaper and magazine articles, and the content of some Web sites (Notice, I said “some.”). By virtue of a process of slow, deliberate, careful reading, you will be able to observe how to construct well-written sentences, use punctuation correctly, and vary your vocabulary.

This is a time-honored technique. It is said that Abraham Lincoln, who attended country schools only intermittently as a youngster, developed his prodigious oratorical and speech writing skills by devoting his undivided attention to reading.

This process of careful reading is very easily done. All that is required is a well-written reading selection and your ability to concentrate. If you want to make notes, then you should do so on a notepad or right on the text (as long as it is yours, and not the property of the public library). You might want to mark significant pages with paper clips so that you may refer to them at a later point.

In order for this to be an effective learning technique, you must be prepared to devote all of your attention to the task, so the television must be off, the kids must be out of sight, and you must be focused. Just about the only reading materials that might be unsuitable for this task are those found on the Internet because, by and large, they are not subject to rigorous proofreading, review, or editing, so quite a lot out there in cyberspace, while interesting, is poorly written. Much of it defies the rules of Standard English usage.

That said, the process is very simple: just read and observe; when you come across a sentence or phrase that contains something of interest, note or underline it and mark it with a paper clip, if you want. Notice the author’s use of periods, commas, apostrophes, quotation marks, colons, semi colons, and exclamation and question marks. Observe the composition of complete sentences. Notice that a well-constructed sentence may be long, as long as it communicates one complete thought. Take note of the fact that a well written piece relies on a variety of words. Rather than repeatedly using the word “take,” a skilled writer will substitute “obtain,” “attain,” “gather,” and “acquire,” along with other synonyms.

If you have a specific question that you would like answered or a problem to be solved, at some point in your reading, you will probably come across a sentence which will provide you with the information for which you have been searching. If, for example, you are unsure about how to properly place quotation marks in a section of dialogue, when you come to one of those sections (with which novels abound), read it carefully, underline or note it in the margin of the book, and clip it. Look at the following example from To Kill a Mockingbird by Harper Lee:

“Give me those scissors,” Atticus said. “They’re no things to play with. Does this, by any chance, have anything to do with the Radleys?”
“No sir,” said Jem, reddening.

Just by reading, observing, and noting, you can learn a great many of the fundamentals of writing. While you are conducting this exercise, you need not deprive yourself of the pleasure of reading. So, read, enjoy, and learn at the same time.

A Novel Approach to Editing


In general, editing a work of fiction involves allowing more flexibility and variation in wording than the standard type of editing that is used for non-fiction documents. As works of fiction, short stories and novels often contain idiosyncratic language and usages which would, in an essay, newspaper article, research paper, letter, or other type of non-fiction writing appear to be incorrect.

For starters, since short stories and novels almost always include dialogue, both exterior and interior, and since conversational language does not always adhere to the rules of written usage, the editor must ignore what appear to be errors. Here is an example of dialogue which includes non-Standard English from Lonesome Dove by Larry McMurty:

“Lord, it ain’t been dry yet,” Pea said. “It’s rained aplenty.”

Notice that, despite the fact that the dialogue contains variations from Standard English in terms of the use of “ain’t” and “aplenty,” the punctuation and the tag (Pea said) are correctly written. Punctuation and proper designation of tags are essential in all works of fiction. (However, all bets are off when it comes to poetry. Language in poetry can range from Standard English to the bizarre. It can be edited only for style and appeal, not for adherence to Standard English.) Proper spelling should also be used, even in dialogue. However, there are times when an author wants a character to mispronounce words or to use inappropriate words or speak in a dialect. In those cases, those altered words should be written in italics and/or spelled out phonetically so that the reader understands that they are variations from the usual spelling. In the following example of the use of dialect from Hard Times by Charles Dickens, the author does not use italics, but he does use phonetic spelling:

“I ha’ thowt on ‘t, above a bit, sir. I simply canna coom in. I mun go th’ way as lays afore me. I mun tak’ my leave o’ aw heer.”

In most cases, portions of narration conform to the rules of English usage. Therefore, those portions of works of fiction should be edited in the same way as essays, research papers, letters, etc. In some cases, however, the author wants the narrator’s use of language to vary from the standard. Look at this example, which is the first sentence of Huckleberry Finn:

You don’t know me without you have read a book by the name of The Adventures of Tom Sawyer; but that ain’t no matter.

Of course, if Mark Twain had wanted the narrator to speak in standard English, the sentence would have been written as follows:

You will not know of me unless you had read a book by the name of The Adventures of Tom Sawyer; but that does not matter.

Authors of works of fiction often use, along with full sentences, short phrases for emphasis. In the following example from The Color of Water by James McBride, the first sentence is full and complete, but it is followed by two declarative phrases, which are not full sentences:

Helen didn’t come home that night. Nor the next day. Nor the next.

Notice the use of the contraction didn’t. In serious non-fiction pieces, the use of contractions is frowned upon. In fiction, contractions are acceptable at all times.

If that portion of narration had been part of a non-fiction document, it would be written as follows:

Helen did not come home night, nor for the next two nights.

In general, when editing works of fiction, the rule is that portions of narration should conform to all of the rules of English usage unless the author wants the narrator’s voice to vary from the standard. Short phrases which are not complete sentences should not be altered. Contractions should be allowed. Portions of dialogue should be left as they are written, regardless of how far removed from proper English usage they appear to be. However, all rules of punctuation should always be adhered to throughout the manuscript. Correct punctuation is necessary in order for the reader to be able to understand what the narrator or character is saying.

Remember, the goal of writing is to communicate. If the reader is unable to understand what is written, then the piece of writing, whether it is fiction or non-fiction, is not fulfilling its goal.