英语语法必刷第九部分：动词的时态语态

56. (单选)

56. [单选]

In the 1950s in the USA, most families had just one phone at home, and wireless phones （　　） yet.

（A）haven't invented

（B）haven't been invented

（C）hadn't invented

（D）hadn't been invented

答案:

解析: