.________they were singing, the teacher came in. A．BeforeB．afterC．AsD．Until

题型：不详难度：来源：

.________they were singing, the teacher came in.

A．Before

B．after

C．As

D．Until

答案

解析

表示正当什么时候，用as

举一反三

I was about to leave my house________the phone rang.

A．while

B．when

C．as

D．after

题型：不详难度：| 查看答案

While playing ping-pong, our eyes see the ball coming, judge its speed and then hit it back ________ it should go.

A．when

B．why

C．what

D．where

题型：不详难度：| 查看答案

It’s not until no enemies were left that they________ .

A．did not stop fighting	B．did stop fighting
C．stopped fighting	D．have stopped fighting

题型：不详难度：| 查看答案

I hurried________I wouldn’t be late for work.

A．since

B．so that

C．as if

D．unless

题型：不详难度：| 查看答案

It was not long________the whole country rose up and drove the enemy out of their country.

A．when

B．before

C．after

D．until

题型：不详难度：| 查看答案