As a teacher, I seldom give my students so difficult a problem they can’t work out.
A. that
B. as
C. if
D. in order that
网友回答
A. that
(答案→)B. as
C. if
D. in order that
解析：句意：做为一名老师，我很少给学生他们做不出的很难的问题。这里是定语从句，先行词是so difficult a problem，定语从句中缺少宾语，如果先行词被as，so，the same修饰的话，用as引导定语从句，而且as在定语从句中做主宾表，选B。