题目内容：

They did what they could____the poor children.为什么填to help 不填help呢?

优质解答

to help...
The did (what they could) to help the poor children...
what they could 是宾语从句.所以.简化整个句子是
They did sth to help the poor children...
翻译起来就是.他们尽其所能地帮助贫穷的孩子.