How often do you do it
一次───once;你───you
Hearing that there was an emergency case, the doctor put down his chopsticks and left at once.───听说有急诊, 医生撂下筷子就走.
He once lived in Zambia.───他曾在赞比亚生活过。
If you find anything wrong with the machine, you should put it right at once.───发现机器有故障, 要及时排除.
I have been there once.───我到过那儿一次.
Once you've given your word, don't try to back out.───一旦许下诺言, 就不要想翻悔.
Slavery was once socially sanctioned.───奴隶制曾经为社会所认可.
You want to see a doctor at once.───你必须马上去看医生.
She guessed the right answer at once.───她立刻猜出了正确的答案.
Once on shore, we pray no more.
The valiant never tastes of death but once.
Once water begins to boil,its temperature no longer rises.
If necessary I can come at once.
She determined to go at once.