Whether we teach formal ESL courses or not, nearly all our faculty will have students for whom English is a second language. You will find some of the errors listed here in the writing of native speakers of English, but some (such as articles and preposition problems) are particular to writers for whom English is a second (or third, or fourth) language.
Number One: Articles
Articles are perhaps the most persistent problems for non-native speakers of English, especially for Asian or Russian writers, whose languages don’t use articles. Occasionally, European speakers will exhibit some difficulty with articles as well: in many languages, every noun requires an article, and it is unclear to some speakers when articles should be omitted. A Native English speaker (even a young one) will never have trouble with articles: we know at some fundamental level when to use or to omit “the,” “a,” or “an.”
The basic rules for articles are not hard to explain: countable nouns require articles; uncountable nouns generally do not. Reference to a concrete noun generally requires a definite article; reference to an abstract noun usually requires an indefinite article. What complicates the matter is that article use depends often on context, both grammatical and in terms of a sentence’s meaning. For example, “Society disapproves of smoking,” is one context, while “The society of non-smokers lobbies hard to take away smokers’ rights,” is another.
What makes this problem even more difficult to explain is that some article use is idiomatic, or requires a lot of grammatical analysis in order to be understood. For example, why say “I have a cold,” but then say “I have pneumonia”? Why not say “I have a pneumonia?” And why do we invite someone out to dinner, not out to the dinner, or a dinner? (Though we will always invite them out for a meal, not simply meal.)
You will do a lot of intellectual sweating attempting to help writers with articles, and you will be tempted to pass off most of what is hard to explain as idiomatic. Resist this temptation! Perhaps the usage is idiomatic, but an attempt to explain and to understand the finer points of grammar can be useful for students.
Number Two: Prepositions
This is a second area of error that is almost exclusive to ESL writers. While some New Yorkers will wait on line (instead of in line, like the rest of us), for international writers the problem of prepositions is much more serious. Beginning writers will have trouble understanding why it is that sitting by the table is different from sitting at the table; more advanced writers will have trouble wrestling with the difference between being concerned with something, as opposed to being concerned by something.
Typically those prepositions used to express abstract thoughts will be particularly meddlesome: an ESL writer may be able to visualize the difference between being on the water and in the water, but less able to see the difference between dwelling in and dwelling on a particular idea and emotion. Unfortunately, most preposition usage is simply that: a matter of usage. The best you can do is to explain differences to the writer, and to hope that s/he will take your explanation with him/her into the next paper or next conversation with a native speaker.
Number Three: Infinitives
Another category of error common to ESL writers is incorrect use of infinitives. You will find that ESL writers will pattern their English sentences after sentences in their native languages, where often many rules (including the rules for infinitives) differ from the rules we use in English. Therefore, you will have writers composing sentences like, “I wouldn’t mind to have a BMW.” There are categories of verbs that call for the infinitive, and other categories that do not.
Number Four: Using the Wrong Parts of Speech
ESL writers will sometimes confuse parts of speech, using an adjective where they want to use a noun, or a verb where they want to use a gerund, or an adverb where they want to use an adjective. This is common when one is learning a foreign language (those of you learning German, French, Italian, etc. surely make the same kinds of mistakes). Be patient: usually pointing to the word in question is enough to make the writer hit himself in the head, utter some word that you don’t understand, and provide the proper word for him-/herself.
Number Five: Agreement
Subjects and verbs must agree, tenses must agree, and so on. While this category of error is not exclusive to ESL writers, agreement errors are especially likely to plague ESL papers.
To be Continued with Errors #6-10…