首先_his mother wouldn't allow him to
是一个句子
所以链接表语从句的就是that
前面这个reason是做gave的宾语
而不是副词
所以用连接词which
如果是这样The reason_he didn’t come was_his mother wouldn't allow him to.
这里就要用why了
体会这两点的不同吧
综上 选D
首先_his mother wouldn't allow him to
是一个句子
所以链接表语从句的就是that
前面这个reason是做gave的宾语
而不是副词
所以用连接词which
如果是这样The reason_he didn’t come was_his mother wouldn't allow him to.
这里就要用why了
体会这两点的不同吧
综上 选D