We should do what we can to reduce crime中what在从句中充当什么成分呢?

问题描述:

We should do what we can to reduce crime中what在从句中充当什么成分呢?

what=the thing( that.)
what既是do的宾语,又是从句的宾语.可是从句中what we can没有谓语动词啊what we can (do)为什么要把do给省略了呢惯用法