Solution:
No sooner is used to show that one thing happens immediately after another thing.No sooner does sir ask a question than clever students give an answer.
591. He has been living in Switzerland . . . . . . . . two years.
Solution:
The preposition 'for' is used to denote a specific amount of time in which someone or something was performing an action. For example, 'I have been looking for my dog for some time now.' Here, 'for some time now' represents not an exact but particular amount of time. The word 'since', on the other hand, refers to a particular point of time from when the action started/began in the past to the present. It indicates that the action is continuing. For example, 'Raj has been living in London since 2003.'
Here are a few more examples to help you understand how the two prepositions are used.
Bruce has been travelling for the past two weeks.
Neethu will be here for a few hours.
I have known you since you were a kid.
Shanti has been working as a content writer since 2018.
Solution:
In the above sentence, a preposition is missing. And without a preposition the sentence is incomplete.
A preposition is a word that shows the relationship between a noun or a pronoun and some other word or element in the rest of the sentence.
The most suitable prepositions for the given sentence can be for, about etc.
594. The accident occurred when the passengers . . . . . . . .
Solution:
The sentence is in past continuous. We use was/were + the -ing form of the verb. We generally use the past continuous to talk about actions and states in progress (happening) around a particular time in the past. It can emphasize that the action or state continued for a period of time in the past.
