Professor James will give up a lecture on the Western culture,but when and where yet.
A. hasn’t been decided
B. haven’t decided
C. isn’t being decided
D. aren’t decided
网友回答
(答案→)A. hasn’t been decided
B. haven’t decided
C. isn’t being decided
D. aren’t decided
解析：现在完成时表示已经完成动作或从过去某个时候开始一直延续到现在的动作。根据时间状语yet可判断出要用现在完成时。因为when and where作decide的逻辑宾语，所以要用现在完成时的被动语态，表示“什么时候和地点还没有确定”。现在进行时表示说话时正在进行的动作或事件。