Abdul Gaffar Khan was the leader of Civil Disobedience movement in Peshawar.

The correct sentence should be:

Hardly had we stepped out of the building when we got drenched.

Explanation: The phrase "then we get drenched" should be replaced with "when we got drenched" to maintain the correct verb tense. "When" is the appropriate subordinating conjunction to use in this context.

The correct sentence should be:

I couldn't sleep because I was very tired.

Explanation: The phrase "in case of being very tired" is awkward and not commonly used in English. Instead, you can use the phrase "because I was very tired" to clearly express the reason for not being able to sleep.

The Jallianwala Bagh massacre, also known as the Amritsar massacre, took place on 13 April 1919.

The underlined segment in the given sentence does not need substitution. It is already grammatically correct:

The Ghats in Benaras were very crowded but we were able to watch the Ganga aarti clearly.

The correct sentence should be:

He couldn’t believe it at first, so the more he thought about it, the more he decided it must be true.

Explanation: The phrase "the most he thought about it" should be replaced with "the more he thought about it" for the sentence to be grammatically correct. The phrase "the more" is used to indicate an increase in intensity or degree, which is appropriate in this context.

The correct sentence should be:

This appears to be the handiwork of someone who belongs to a criminal gang.

Explanation: The original sentence has a verb tense issue. "To belong" should be replaced with "belongs" to maintain the correct present tense form in this context.

The correct sentence should be:

Four people were injured after a car suddenly came to a halt in outer Delhi.

Explanation: The phrase "came to a halt" is the correct idiom, indicating the action of stopping suddenly. The original sentence, "came for a halt," is incorrect.