问题补充：
This math problem is too difficult. Can you show me, George?
A. what to work out
B. to work it out
C. how to work it out
D. how to work out it
答案：
A. what to work out
B. to work it out
(答案→)C. how to work it out
D. how to work out it
解析：考查“疑问词+不定式结构”和动词短语。work out是动词+副词短语，故代词作宾语时，要放在动词和副词之间，这里是疑问词加不定式在句中作宾语，根据题意是指“如何解答出来”，故选C。
