问题
选择题
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
答案
答案：C
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。