问题补充:
The theory he had stuck to be true.
A. proved
B. to proving
C. to prove
D. to proved
答案:
@@A. proved@@B. to proving@@C. to prove@@(答案→)D. to proved
解析:一看这四个选项认为是不定式后接动词原形,其实he had stuck to是充当后置定语,stick to(坚持)为一个固定搭配,去掉这个定语从句后,我们可以很清楚地发现整个句子缺少了谓语动词,定语从句时态为过去完成时,所以主句谓语动词应该过去式。