【题目】It is _____ problem that none of us can work it out.
A. so difficult B. such difficult a
C. such difficult D. so difficult a
在线课程【答案】D
【解析】
考查so---that引导的结果状语从句。句意：这是一个如此困难的问题，我们谁也解不出来。此处是so+形容词+a/an +名词 that引导的结果状语从句，相当于such+ a/an +形容词+名词+that引导的结果状语从句。故选D。