问题
选择题
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
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。