Professor James will give us a lecture on the Western culture but when and where yet. A

问题补充：

Professor James will give us 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

答案：

(答案→)A. hasn’t been decided

B. haven’t decided

C. isn’t being decided

D. aren’t decided

解析：

A。根据句意，此处应用被动语态，不用主动语态; 再根据句末的yet可知，最好用现在完成时。故选A最佳。