Ordinal Numbers. Notice the form for second and third is d and not nd or rd.

For example:
Bjorn was given the 232d and 233d numbers our of 655.

Capitalize language and those school subjects followed by a number.

Do not capitalize general school subjects unless the subject is a language.

Languages: Arabic, English, Korean, Polish, and etc.

School Subjects: Biology 403, French, history, literature, Social Science 101, statistics, and etc.

When a subordinate clause introduces a complex sentence, it is usually followed by a comma unless it is very short.

For example:
When you come in the front door, make sure you push it shut, because the lock doesn't always catch.

Avoid putting the preposition at the end of a sentence.

Avoid: They were not sure which college they should apply to.
Better: They were not sure to which college they should apply.
(The preposition is now part of the phrase to which college.)

Avoid: Ask not whom the bell tolls for.
Better: Ask not for whom the bell tolls.

Common errors involve msiplacing the adverb only

The position of the adverb can affect the meaning of the sentence. The most common error involves misplacing the adverb only. Make sure that the adverb position conveys what you intend to say.

Example 1
Unclear: We only walked to the store and not to the bank.
(Did the speakers only walk and not run? Or did they walk only to the store and not elsewhere? The meaning is unclear.)
Clear: We walked only to the store and not to the bank.


Example 2
Unclear: She frequently calls the magazine editor. (Does she calls the magazine editor more frequently than she calls anyone else? Or does she simply call the editor many times [frequently]?)
Clear: She calls the magazine editor frequently.

Do not use would have in "if clauses" that express the earlier of two past actions. Use the past perfect.

Correct: If he had thought of it, he would have asked you to ride with us.
Incorrect: If he would have thought it, he would have asked you to ride with us.

Use the past perfect tense to refer to the event or action in the more distant past

When describing two events in the past that did not occur at the same time, use the past perfect tense to refer to the event or action in the more distant past.

Correct: I suddenly remembered that I had left my purse at the office.
Incorrect: I suddenly remembered that I left my purse at the office.

(Because leaving the purse at the office preceded remembering the fact, the past perfect form of had left should be used.)