Betty is often seen___(help)the old man with his housework.

题目

Betty is often seen___(help)the old man with his housework.
答案为什么是to help啊?helping行不行?

答案

Betty is often seen (to help) the old man with his housework.
贝蒂经常被人看见帮这位老人做家务.
see sb do,看见某人做某事.变成被动语态就是be seen to do,被人看见做某事.所以这里要填不定式.