Could you tell me whom the radio __ by?Sorry,I have no idea.

问题描述:

Could you tell me whom the radio __ by?Sorry,I have no idea.
请问这个句子是什么意思 为什么用过去式的被动语态?
Could you tell me whom the radio __ by?Sorry,I have no idea.
C:is invented D:was invented

D 显然这个收音机已经被做出来了.