问题补充：
The maths problem is so difficult that none of them can .
A. work out it
B. work it out
C. find out it
D. find it out
答案：
A. work out it
(答案→)B. work it out
C. find out it
D. find it out
解析：句意：这个数学问题太难了以至于他们中没有一个人能够解出来。work out意为“解决出”；而find out意为“发现、找出”；这两个短语都属于动词+副词构成的短语，后面跟代词时需要将代词置于中间，所以A和B结构错误；故选B。
