It is clever _ you ti work _ such a difficult maths problem within ten minutes.

题目

It is clever _ you ti work _ such a difficult maths problem within ten minutes.
A.for,at B.for,out C.of,out D.of,on

答案

C
work out是固定搭配,意思是算出 排除AD
第一个空是说 你聪明 不是 所以用of
就像good for you good of you 是你人好