【题目】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】D
【解析】二十世纪五十年代在美国，绝大多数家庭只有一部电话，无绳电话还没有发明出来．句中invent与主语phones构成动宾关系，要用被动语态；invent的动作发生在谓语动词had之前，是过去的过去，要用过去完成时态的被动语态．故选D．