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King’s College London

Common Grammar Errors, Updated 22/9/09 [BDM, Geography]

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The Confusion of the Apostrophe
This is a guide to common grammar errors. If you find errors, please email bruce.malamud@kcl.ac.uk. (A) It’s/Its (1) It’s is a contraction meaning it is or it has. For instance, “It’s a rainy day.” In formal essays, do not use contractions. Examples of othercontractions include: they’re (they are), we’ll (we will), don’t (do not). (2) Its is the possessive form of it. There is no apostrophe. For instance, “The cat carried a hat on its head.” [The head belongs to the cat.] (B) Their/There/They’re (1) They’re is a conjunction of they and are. For instance, “They’re going to Spain.” Again, in formal essays avoid using contractions. (2) Their is the possessiveform of they. There is no apostrophe. For instance, “The people carried their umbrellas.” [The umbrellas belongs to the people.] (3) There indicates a place. For instance, “Have you been there?” There can also act as the meaningless subject of a sentence. For instance, “There is a large amount of flooding in England.” (C) Possessive (where to put the apostrophe)
Possession is often indicated inEnglish by adding ’s or ’ at the end of the noun indicating the possessor. Unless one is trying to indicate possession, the plural of a word does not use an apostrophe (except in the rare case where confusion would result if an apostrophe were not used, see number 7 below).

(1) (2) (3) (4) (5) (6) (7)

One cat has one hat: One cat has several hats: Several cats have one hat: Several cats haveseveral hats: Digital elevation models: The period 1980–1989: Beth’s grades were A, A, A, and B:

The cat’s hat. The cat’s hats. The cats’ hat. The cats’ hats. DEMs [not DEM’s] The 1980s [not 1980’s] Beth received three A’s and one B. [“three As” is confusing]

(D) Effect/Affect
Affect with an a is usually a verb; effect with an e is (usually) a noun. When you affect something, you have aneffect on it. The usual adjective is effective. A more complete description of the different uses of affect and effect:

(1) Affect can be used as a verb meaning “to put on a false show of,” as in “She affected a British accent.” (2) Affect can also be used as a noun meaning “emotion,” a technical psychology term that sometimes shows up in general writing. An example is this quote from a NormanMailer piece about the Gulf War: “Of course, the soldiers seen on television had been carefully chosen for blandness of affect.” (3) In its far more common role as a verb, affect usually means “to influence,” as in “The Surgeon General’s report outlined how smoking affects health.” (4) Effect as a noun means “a result.” Thus if you affect something, you are likely to see an effect of some kind, andfrom this may arise some of the confusion. (5) As a verb, effect means “to bring about or execute.” Thus, using effect in the sentence “The measures have been designed to effect savings” implies that the measures will cause new savings to come about. But using affect in the very similar sentence “These measures may affect savings” could just as easily imply that the measures may reduce savings thathave already been realized. (E) Abbreviations/Acronyms Abbreviations and acronyms are frequently used and save time as a shorthand way of communicating. However, when writing essays, it is important to spell out the term to be abbreviated the first time it is used, unless it is a very common abbreviation or acronym. Only use an abbreviation or acronym if it will genuinely save space and not causeconfusion. At the first occurrence, give its complete form, followed immediately by its abbreviated form in parentheses (or put the abbreviated form elsewhere in the sentence):
The project was a joint venture with Lawrence Livermore National Laboratory (LLNL). The project was a joint venture with LLNL, the Lawrence Livermore National Laboratory.

(F) Overexaggeration When writing an essay,...