Incorrect: Each of these girls sing well.
Correct: Each of these girls sings well.
Incorrect: None of my student attended the class today.
Correct: None of my students attended the class today.
Incorrect: One of my servant has gone on leave.
Correct: One of my servants has gone on leave.
Incorrect: Some of my servants has gone on leave.
Correct: Some of my servants have gone on leave.

Explanation

The noun following one of, none of, some of and similar expressions must be plural in number, but the verb agrees in number with the subject of the sentence. In the sentence ‘Each of these girls sings well’, the real subject is each which is a singular word. It should therefore be followed by a singular verb.

Other singular words which often cause confusion are: every, either, neither, none, much and person.

Incorrect: Some of my friends has decided to go on a picnic.
Correct: Some of my friends have decided to go on a picnic.

Explanation

Some is a plural word. It must be followed by a plural verb.

Incorrect: Both did not come.
Correct: Neither came.

Explanation
The expression both…not is not correct in standard English. Instead, we use neither.

Incorrect: One should respect his parents.
Correct: One should respect one’s parents.

Explanation

One, if used in a sentence, should be used throughout.

More examples are given below:

One should take care of one’s health.
One should love one’s country.

Incorrect: One should work hard.
Correct: A man/woman/boy/girl should work hard.

The sentence ‘One should work hard’, is not wrong but in standard English the use of one as subject should be avoided when possible.

Incorrect: Here is the bottle: please fill.
Correct: Here is the bottle: please fill it.
Incorrect: Have you a pen? I have not got.
Correct: Have you a pen? I have not got one.
Incorrect: He enjoyed at the party.
Correct: He enjoyed himself at the party.

Explanation

The verbs fill, enjoy and got are transitive. All transitive verbs must have an expressed object.

Incorrect: I asked for his bicycle but he didn’t lend me.
Correct: I asked for his bicycle but he didn’t lend it to me.
Incorrect: Please give your book.
Correct: Please give me/him/her/them your book.

Explanation

Some transitive verbs like give and lend must have two expressed objects.