He said he ______ work hard to catch up with others .(原因顺便说一下)

题目

He said he ______ work hard to catch up with others .(原因顺便说一下)
A.is willing B.was willing C.is willing to D.was willing to

答案

D. was willing to
be willing to do sth 愿意做某事
这里主句是一般过去时 ,所以从句用了过去将来时