问题

Have you ever visited the Water Cube?— YesWhen I served as a volunteerin Beijing, I it twice.[ ]

A: have visited
B: visited
C: had visited
D: had been visiting

正确答案是：

同类题型

I don’t know where to find something about the rainforest.—Why ______on the Internet There is a lot of information about it.

People ____ in the factory can have ____day off.

Mom，Dad is smoking again!—Well，let him cut it ________ gradually since old habits die hard.

They say that_______a lot of water is good for you.

How did he ______ the punishment he was given for his cruel conduct—No reaction at all. He knew unkindness often reacts upon the unkind person.