the boy who is standing ad the door is my brother.

问题补充：

the boy who is standing ad the door is my brother.这句话去了从句以后主句就剩the boy了句子还对吗?

答案：

这句话去了从句以后是：

the boy is my brother.

成分是完整的,所以是正确的句子.

“从句”本身这个概念就是 附属,从属,所以它本身不影响句子的成分的完整性,只影响句意的完整性.