By the time he ________ the railway station, the train ________.

[　　]

Peter, as well as the other children who ________ no parents, ________ good care of in our country.

[　　]

There are 150 books on the desk, two-thirds ________ to Marlowe.

[　　]

Once lost, ________.

[　　]

A．it is hard to get such a chance again

B．one can never get such a chance again

C．to get such a chance will be difficult

D．such a chance might never come again

Bob ________ hard, otherwise he ________ this exam.

[　　]

A．can't have worked; wouldn't have failed

B．can't work; wouldn't have failed

C．mustn't have worked; wouldn't fail

D．mustn't have worked; would fail

The mother didn't know ________ to blame for the broken glass as it happened while she was out.

[　　]

Neither side was willing to give in at all and so no agreement ________.

[　　]

－What do you think of the computers in this shop?

－Quite good, but I can't afford to buy ________.

[　　]

－You know the exact date ________ you posted the letter, don't you?

－No. But I remember it was a holiday ________ happened to be Mother's Day.

[　　]

They demanded that the books ________ to the school library at once.

[　　]