This is the reason—— he didn"t come to the meeting 为什么不用that?

问题描述:

This is the reason—— he didn"t come to the meeting 为什么不用that?

这是一个状语从句 the reason why 的搭配用法 ,怎样知道他是状语从句还是定语从句呢定语从句都有先行词 这里没有先行词啊