Question

Although the teacher had told Bob the history of telephone, Bob didn’t know when ____.

A. it was invent       B. was it invented       C. it was invented    D. it invented

Answer

C

【解析】考查宾语从句和被动语态。句意为：尽管老师给鲍勃讲了电话的历史，但他还是不知道电话是什么时候发明的。首先，宾语从句要用陈述句的语序，即：连接词+主语+谓语+其他，所以B不对；另外，it（电话）是invent（发明）的承受者，所以要用被动语态（be+过去分词）。故选C。

考点：考查宾语从句和被动语态的用法。