时间：2023-01-13 18:40
1、常见句型
(1)用作副词
I have been there once.
我到过那儿一次。
I once went around the world.
过去我周游过全球
(2)用作连词
Once you begin, you must continue.
一旦开了头,你就必须继续下去。
Once you have taken the examination, you'll be able to relax.
你一旦考过试,就可以轻松一下了。
Once you have promised you must do it.
你既已答应,就应该去做。
Once inside her bedroom, she began to cry.
一走进卧室,她就哭了。
(3)用作名词
Once is enough for me.
我一次就够了。
She's only done it the once so don't be too angry.
她只做过这一次,所以不要太生气。
2、词义用法
once用作连词时可引导时间状语从句和条件状语从句。用于前者时意为“一旦…就…”,引导的从句多很短; 用于后者时意为“只要”,这种条件从句似带有时间条件的含意。once引导的从句中有些部分可以省略。
3、词汇搭配
once in a blue moon 罕见的，极少的，难得...at once 立刻once or twice 一两次all at once 同时once and for all 彻底地once upon a time 从前once bitten, twice shy 一朝被蛇咬,十年怕井...once more 再一次once again 再一次once too often 又一次once in a while 偶尔once and away 一次了解地not once 一次也不more than once 不止一次(好几次)...once and again 一而再gone 过去的for once 就这一次every once in a while 间或once in a way 有时，偶而for this once 就这一次
