Common English Mistakes by Graduate Students

1. Number agreement between subject and verb: In English, nouns and verbs have number (i.e. singular: one, and plural: more than one). Quite often, but not always, the plural of a noun is formed by adding "s" or some variant, as in "computer" --> "computers", "matrix" --> "matrices", etc. The opposite is true for verbs: a plural verb will often have no "s", but the singular version is obtained by adding "s": "computes" (singular) --> "compute (plural). Thus, "computers compute using electronics", but "this computer computes using electronics". We say "the scheme utilizes . . ." but "the schemes utilize . . .". (One might formulate this as the "conservation of s" law.) Not all verbs follow the "s" pattern; for example "are" is the plural form of "is", "had" is both singular and plural, "criteria" is the plural of "criterion", "data" is the plural of "datum", "media" is the plural of "medium", etc. Check a dictionary if in doubt.
2. Number in possessive pronouns: "their" refers to several possessors, while "its", "his", and "her" refers to a single one. ("John and Mary use their personal computer to . . .", "The computer gets its power from . . .")
3. Its: "its" is a possessive pronoun. "it's" is a contraction of "it is". The two are not interchangeable.
4. Dangling prepositions: Phrases should not be ended with prepositions (e.g. "to", "with"). For example, instead of "the output port the memory is connected to" use "the output port to which the memory is connected". A good way of remembering this is to recall the tongue-in-cheek rule: "A preposition is something you should never end a sentence with".
5. Generic versus specific: Different constructions are used for generic and specific statements. We say "computers compute" when we are talking about computers in general, but "the computer computes" when we are talking about a specific computer (mentioned earlier usually). The word "the" is called the "definite article", because it refers to a specific thing or set of things ("article" is the term used for words "the", "a", "an"). The article "the" is used for both ("the computers in MEB"). The plural generic uses no article ("computers compute using electronics"). The singular generic used "a", as in "a computer computes using electronics".
6. "a" vs. "an": The article "an" is used before words which begin with a vowel sound, whereas "a" is used before words which begin with a consonant sound.
7. "good" vs. "well": There are two kinds of modifiers: adjectives, which modify nouns, and adverbs, which modify verbs or adjectives. "good" is an adjective ("It is a good scheme".) while "well" is an adverb ("The scheme works well".).
8. Discrete vs. continuous (or countable vs. uncountable): The words "many", "few", and "several" refer to discrete objects ("There are few computers which . . .", "Several algorithms exist for . . ."). The words "much" and "little" refer to uncountable commodities ("I have little patience . . .", "There is much to be learned . . .", but "There are many things to be learned . . ."). Similarly, "less" is continuous, while "fewer" is discrete: "Give me less soup and fewer beans"; "more" is used for both: "Give me more bananas and more water". (But some things with a discrete character are discussed as if they were continuous: "My program uses less memory", but "My data require fewer bits".)
9. Commas should be used where you would normally pause if you were reading the sentence aloud. However, they should be used only where there is possible ambiguity in parsing the sentence without them.
10. "like" vs. "as": "like" is used to compare two similar things or concepts: "A circulating memory is like a shift register". "as" is used to conjoin phrases: "A circulating memory behaves the same as a shift register".
11. Inappropriateness of verb to subject, e.g. "Computers as inanimate machines argue for intelligence in their use" ("Computers" do not "argue", etc.). Examine each sentence to locate the subject and verb, and be sure they make sense as isolated pairs.
12. If you have trouble expressing a complex sentence, it most surely should be broken into two or more new sentences.

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