The boy ________is helping the old man is John's brother

问题描述:

The boy ________is helping the old man is John's brother
用疑问代词填空

The boy that /who is helping the old man is John's brother
这是一句定语从句,填的是关系词
先行词【boy】在从句中作主语,又指人,所以用【that/who】