Verb Gap Fills

Case of past indefinite tense. Second form of the verb is used in such cases. Second form of 'go' is 'went'.

All the clauses of the sentence need to follow the same tense.

It is a case of 'seeking permission'. 'Could' is used in a polite manner, i.e. to seek permission for something.

Case of verb of being (present tense). The subject (book) is a singular noun and needs singular auxilary. Thus, option 1.

Case of past continuous tense. 'Reached' is past of 'reach'. In such cases we use 'was/were + verb+ing'. Thus, option 3.

Case of present perfect tense (as proved by usage of 'till now'). In such cases we use 'has/have + third form of the verb'. Thus, option 4.

Case of future indefinite. Pronoun 'you' is always followed bu a plural verb. Hence, 'give'.

The sentence is the case of 'slight probability' of happening something. And to reflect 'slight probability' we use 'might'.

Case of past indefinite tense. Some words like 'last week' always take second form of the verb. Thus, option 4.

Case of verb of bbeing (present).  The blank qualifies to Dr. Devi (singular noun). So, singualr auxilary is needed to fill the blank. Thus, option 2.

The sentence implies that it is the duty of the second person to have informed the first subject earlier. It is a case of implicit 'responsibility'. In such cases, we use 'should'.

This is a case of future tense. We use 'shall' with the first person (i.e. I). 'Shall be here' means 'I shall be available here only'.

Case of present indefinite. Whenever an event of near future is scheduled to happen, we use present indefinite. In such cases we use 'is/are + verb+ing'.

Case of past perfect tense. Whenever we mention about two incidents of the past that happen one after the other, we use 'had + third form of the verb' for the former incident.

Words like 'yesterday' always take second form of the verb. 'Did' is the second form of 'do'.

Case of present perfect continuous tense. Whenever an activity of past continues till the present time, we use present perfect continuous tense. 'Has/have + been + verb+ing' is used.

Case of future indefinite. Whenever two incidents of future are supposed to happen one after the other, we use 'will/shall'  with the latter.

To show somebody's possession, we use 'has/have'. For singular third persons we use 'has'.

Case of verb of being. To show somebody's possession, we use 'has/have'. With singular third person, 'has' is used.

Case of past indefinite. Some words like 'yesterday' always take second form of the verb.

Cae of past perfect tense. Whenever we refer to two sequential incidents of the past, we use 'had + third form of the verb' with the former.

The sentence uses the present perfect tense to describe an action that started in the past and continues to the present. 'Haven't seen' is the correct form for the first-person singular subject.

This is a general fact (present), so case of present indefinite. The blank qualifies to the apple (ie. singular noun). Therefore, we need a singular verb. Thus, option 2.

'Would' is past form of 'will'. It demands usage of past form of the verb. Thus, option 3.

Case of present indefinite. This is a general fact (of present), and 'Earth' is a singular noun. Thus, option 2.