Fill in the blanks with the most appropriate option:-

Many a man …………. tried but few men have succeeded.

has

The correct option to fill in the blank is has.

The idiom "many a man" is used to refer to a large number of men. In this sentence, it means that many men have tried to achieve something, but few have succeeded. The verb "has" is used in the present perfect tense to indicate that the action of trying has happened in the past and has a connection to the present. This is because the fact that many men have tried to achieve something is still relevant to the present, as the fact that few have succeeded is still a problem.

The other options are not as appropriate:

• Were is the past tense of "has", and it would not be accurate to use the past tense in this sentence, as the action of trying is still happening.
• Had is the past perfect tense of "has", and it would not be accurate to use the past perfect tense in this sentence, as the action of trying happened before the action of succeeding.
• No improvement is not correct, as the sentence needs a verb to complete it.