这句定语从句!求帮忙!

题目

这句定语从句!求帮忙!
最近在看雅虎answer里的提问回答.有一个句子是the only thing you can do is talk to her about it,
请问is 后面应该加to吧?
还有一个是 the only thing you can do is be honest with him. 总觉得这里的Is后面应该加to...
求解答

答案

是的,应该加to.因为谓语动词talk和be 不能直接做系动词is的表语,上面两个应加上to,不定式才能作表语.the only thing you can do is 【to】talk to her about it,the only thing you can do is 【to】be honest with ...