waited until he ------- his homework.

很简单的问题
答案只能是 finished 用一般过去时
不能选择had finished过去完成时,因为过去完成时表示过去某事已经完成,如果他已经写完了作业,I waited本句就失去了原义.更何况如果使用过去完成时,那么句中他写完作业这个动作就发生在了我等待这个动作之后,不符合逻辑
原句使用finished 翻译是,我一直等到他写完作业.
另外附上until的语法 lz可以看下
下列情况一般使用until
1.主句是持续性谓语动词时,肯定,否定都可以,但意义完全不同,肯定表示动作终止,而否定表示动作开始.
For example:
1).We discussed the problem until/before he came back.我们一直讨论到他回来.
2).We didn’t discuss the problem until he came back.我们一直等他回来才讨论问题.
2．Not…until…句型尽管在某些情况下可与before互换使用,但在强调句中一般仍用until;
1).It was not until he told me that I knew it.直到他告诉我我才知道这件事.
2).It was not until he finished his homework that he went home.直到完成作业他才回家.
3.放于句首时用until.
For example:
Until he finished his homework ,he didn’t go home.直到完成作业他才回家.
应注意：在使用not until时,若not until放于句首,句子应部分倒装.
For example:Not until he finished his homework,did he go home.直到完成作业他才回家.
希望对你有所帮助 \(≧▽≦)/~啦啦啦