English Grammar and Usage

'When I met him' indicates that the time has passed. Hence, the answer should be 'that'.

1. A snake was killed by me.
   1. You are requested to come daily.
   2. Mahesh is the most intelligent student of the class.

Simple past tense will change to past present form. 

Case of present perfect continuous tense. 'Subject + has/have + been + present tense verb + ing + since/for'.

Pooja and I are two subjects. Hence, a plural verb will be used.

Present continuous tense: ‘Subject + is/am/are + present tense verb + ing + object'.

Future perfect tense: 'Subject + will/shall + have + past participle + object'.

Passive voice of present perfect tense: 'Object + has/have + been + past participle + by + subject'.

'Listening to music' is a perfect example of gerund.

We use 'subject + has/have + past participle' in the present perfect tense.

We use 'subject + was/were + v1 + ing' in the past progressive tense.

We use 'did + v1' in questions of simple past tense.

Only option 4 constructs the sentence correctly. In continuous tense, we use 'auxiliary + verb+ing'.  .

Case of passive voice, where we use third form of the verb with auxiliary.  Also, 'a group' is singular entity, requiring use of singular helping verb 'is'. Option 2 is the correct answer.

Case of passive voice. Option 4 constructs the sentence in present perfect tense.