不要扔掉这些旧书。
____________________________________________
昨天雨下得太大了,我们无法在室外打篮球。
________ that we couldn't play basketball outside yesterday.
格林先生使我们很容易地学习英语。
Mr. Green made it ________ to learn English.
他自从来到我们学校就教我们物理。
________since he came to our school,
昨晚九点你在做什么呢?
________ at nine o'clock last night?
有几个人在门口等你。
________ waiting for you at the door.