Professor James will give us a lecture on the Western culture, but when and where ____ yet.A.hasn't been decidedB.haven't decidedC.isn't being decidedD.aren't decided
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A解析when and where是when and where Professor James will give us the lecture的省略形式，是一个主语从句，谓语动词用单数形式，根据句意可知用现在完成时态表示“至今未定”。
点评:考查主谓一致及时态，偏难。