get up earlier than usual 为什么than 后要用形容词

网友回答

这是一个省略形式,比如说：Yesterday,he got up earlier than usual.原句是Yesterday,he got up earlier than he gets up in the usual time.
======以下答案可供参考======
供参考答案1:
than 是专门用来表示比较级的，所以它前面的都要用比较级