Fill in the Blanks

Has improved signifies completion in the present. His return would be in simple past (some point of time when he came).

The subject 'they' is plural, so the past tense verb 'were' is the correct choice.

 If he tried (past), he would (future of past) succeed. If he tries (present), he will (future of present) succeed.

The sentence describes a completed action in the past, so the simple past 'applied' is the most appropriate verb form.

The subject 'Mohan' is singular, so the present tense verb 'lives' is required for subject-verb agreement.

The sentence is in the passive voice, requiring the past participle 'stolen' with the auxiliary 'was'.

The sentence describes a state of feeling in the past, requiring the passive construction 'was surprised'.

The phrase 'for a long time' indicates a duration that started in the past and continues to the present, requiring the present perfect tense.

Scientific facts are expressed in the simple present tense, even when reported in the past.

This describes a hypothetical past event that did not occur, requiring the third conditional structure 'would have resumed'.

The action of putting on the shirt happened before the change in the evening, requiring the past perfect tense.

The sentence is in the passive voice, requiring the past participle 'sung' with the auxiliary 'was'.

The main clause is in the past tense ('was'), so the modal 'could' is the correct past tense form to express ability.

The sentence is in the past tense ('was'), so the past tense negative 'did not' is required.

The action 'entered' is a completed past action that occurred at the same time as the bell ringing.