until 的用法
until prep.“直到 .为止”；“在 .之前”
conj.“直到 .为止”
一、until 用于肯定句中,主句的谓语动词一般用延续性动词,如 sit,stay,sleep,dance,talk,work,study,wait,play,etc.表示动作一直延续到 until 所表示的时间为止,意为“直到 .为止”.例句：
1）I shall stay here until / till next Sunday.
2）Let's wait until / till the snow stops.
3）We danced and danced until / till a lot of them joined in.
二、until 用于否定句中,主句的谓语动词一般是终止性动词,意为“直到 .才”.例句：
1）The store doesn't open until 9 a.m.
2）She didn't arrive until the meeting started.
注意：
1.not until 放在句首时,主句中的主谓结构要到装.例句：
1）Not until he had gone did she began to work.
2）Not until then did he realize that he was wrong.
2.not until 可用于强调结构中：It is / was not until ...that ....例句：
1）It was not until 9 p.m.that he arrived.
2）It was not until I saw her next morning that I felt happy.
三、until 引导的时间状语从句中,要用一般现在时表示将来的动作.例句：
I'll wait until he comes back.
until / till 当“直到 .为止”讲时,只能指时间,不能指空间.例句：
1）She walked until / till the river.（错句）
2）She walked until / till she got to the river.（正确）