sad的名词形式和副词形式

sad的名词形式为sadness，副词形式为sadly

例句

1.

It was sad that his international career should end in such anticlimax.

令人悲哀的是，他的国际职业生涯竟如此惨淡收场。

2.

Sad home, where no one is waiting for me.

悲哀的家，没有人等我的家。

3.

Those are two very sad words.

这实在是很悲哀的几个字。