Tenses Questions and Answers

Answer: A

The key's answer is is being repaired.

The roof needs a passive verb, since it is the thing repaired, not the one repairing; that rules out 'is repairing', which would make the roof the doer. The word 'now' and the reassurance that you need not worry any longer point to work going on at the present moment, which is what the present continuous passive, 'is being repaired', expresses.

'Was repaired' puts the repair wholly in the past and does not sit with 'now'. 'Has been repaired' is also grammatical and would mean the work is already finished; the key prefers the continuous form that matches 'now'.

Answer: C

The correct form is have developed.

'Over the last fifty years' covers a period running from the past up to now, which calls for the present perfect. Here 'develop' is used intransitively, in the sense of 'grow and change': mobiles themselves have developed dramatically. The adverb 'dramatically' describes that change in the phones.

'Were developed' is simple past and does not fit a period lasting until the present. 'Are being developed' describes work going on at this moment, not change over fifty years. 'Have been developed' makes the phones the object of someone's development work, which fits a sentence about who developed them, not one describing how much the phones themselves have changed.

Answer: B

The answer is have known: They have known each other since their childhood.

The present perfect is formed with have/has and the past participle, and it is used for a state that began in the past and continues now. The word since, marking the starting point, signals it.

Knew is the simple past, which describes a finished period and does not go with since. Knowing is a participle and cannot be the main verb on its own. Find is the wrong verb and in the present tense. Know is a state verb, so the continuous form have been knowing would also be wrong.

Answer: B

The answer is was looking, turned: When they realised I was looking at them, they turned away.

The first blank describes an action in progress at a past moment, so it takes the past continuous, was looking. The second is a single completed reaction, so it takes the simple past, turned, matching realised.

Looked, was turning reverses the two forms. Looking, were turning has no auxiliary for the first verb, so I looking is not a finite clause. Looked, turn puts the second verb in the present tense in a past-tense sentence.

Answer: B

The correct word is would: If he had run fast, he would have won the race.

This is a third conditional, describing an unreal situation in the past. Its pattern is if + past perfect (had run) in the condition, and would have + past participle (would have won) in the result.

Must have won expresses a confident deduction, not a hypothetical result. Had have and was have are ungrammatical, since have after an auxiliary needs a modal such as would, could or might.