that

that 可以代表事，也可以代表人。在从句中可以做主语或者宾语，做宾语时可以省略，但不能用于非限制性定语从句。代表人时，who比that 用的多，代表物时，that 比which用的多。

例如：

The letter that came this morning is from my mother.今天早晨收到的那封信是我母亲寄来的。

Those students that failed the exam will have to take again。考试不及格的学生必须补考。

Have you forgotten the money that i lend you last week? 你忘了上星期我借你钱的事了吗?

All the people that i invited have agreed come。所有我邀请的人都同意来了。

The hotel that that we stayed at was both cheap and comfortable。 我们住的那家旅馆既便宜又舒服。