Explanation

Neither is singular, so it takes has, not have.

Correct sentence: Neither of the two boys has done his work.

Explanation

Explanation

The committee have decided to postpone the event until next month.

Committee is a collective noun and is generally treated as singular in British English: The committee has decided…

Explanation

The parallel structure requires: “both to ride to school and to go to market.”

So “going to” is incorrect; it should be “to go to.”

Explanation

The verb should be “controls”, not “controls over.”

Correct sentence: “The hormone insulin controls the amount of sugar in the blood, which provides energy for the body.”

Explanation

The sentence should be "Sharks differ from other fish in that their skeletons are made of cartilage instead of bone."

The error is in “instead bone”, which must be “instead of bone.”

Explanation

The correct sentence is: "She told the doctor that he had not been sleeping for the previous day." 

The error is the omission of the definite article "the" before "previous day."

The word "previous" is an adjective that needs a determiner like "the" when referring to a specific, singular day. 

Explanation

"Rainfall" is uncountable, so we use "has" not "have."

Correct sentence → There has been heavy rainfall yesterday.

Explanation

The phrase should be “a good friend of mine”, not of me.

"Mine" is the correct possessive pronoun used after “of” in this context.

Explanation

The word “that” is incorrect here; it should be “it”.

Correct sentence: “Sometimes it is difficult to place Physics & Chemistry into separate categories.”