The teacher set such a difficult problem none of us could solve.A. thatB. so thatC. whichD

问题补充：

The teacher set such a difficult problem none of us could solve.

A. that

B. so that

C. which

D. as

答案：

A. that

B. so that

C. which

(答案→)D. as

解析：定语从句考查题。先行词problem有such修饰，关系词只能用as不能用that或 which，as在从句中做solve的宾语。