Inthe1950sintheUSA,mostfamilieshadjustonephoneathome,a...

问题详情：

 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

【回答】

D

知识点：动词时态与语态

题型：选择题