By the end of last month, ten primary schools with the help of Project Hope. A. had set u

By the end of last month, ten primary schools with the help of Project Hope.
A. had set up
B. had been set up
C. was set up
D. set up

A. had set up(答案→)B. had been set up C. was set upD. set up解析：考察时态和语态。本题的关键是by到…时为止；该词引导的时间状语与完成时连用，本题后面跟的是一般过去时。故后面的主句使用过去完成时。句意：到上个月底，在希望工程的帮助之下十所小学已经被建立了。根据句意说明使用过去完成时的被动语态。故B正确。

回答的不错