1. all at once : 突然, 同时；
2. at once : 立刻, 马上；
3. once or twice : 一两次, 几次；
4. once upon a time : 从前；
5. once in a while : 偶尔；
6. once more : 再一次；
7. not once : 一次也没有；
8. once and away : 彻底地, 一劳永逸地；
9. once too often : 又(多了)一次；
10. more than once : 不止一次；
11. once again : 再一次；
12. once and again : 一而再, 再三；
副词
名词
连词
就业和工作
生意场上
Salary-(工资)
1. 一次；一回
If something happens once, it happens one time only.
2. （与后接day, week, month等的a连用）（每…）一次，（每…）一回
You use once with 'a' and words like 'day', 'week', and 'month' to indicate that something happens regularly, one time in each day, week, or month.
3. （与后接day, week, year等的every连用）（每隔…）一次，（每隔…）一回
You use once with 'every' and words like 'day', 'week', and 'year' to indicate that something happens a specified number of times and on a regular basis.
4. 曾经，一度（状况如此）
If something was once true, it was true at some time in the past, but is no longer true.
5. 曾经（做过某事）
If someone once did something, they did it at some time in the past.
6. 一旦…（就…); 一…（就…）
If something happens once another thing has happened, it happens immediately afterwards.
7. 突然；忽然
If something happens all at once, it happens suddenly, often when you are not expecting it to happen.
8. 立即；马上
If you do something at once, you do it immediately.
9. 同时；一起
If a number of different things happen at once or all at once, they all happen at the same time.
10. 就此一次；破例一次
For once is used to emphasize that something happens on this particular occasion, especially if it has never happened before, and may never happen again.
11. 又一次；再次
If something happens once again or once more, it happens again.
12. 彻底地；一劳永逸地
If something happens once and for all, it happens completely or finally.
13. 偶尔；间或
If something happens once in a while, it happens sometimes, but not very often.
14. 一两次；几次
If you have done something once or twice, you have done it a few times, but not very often.
15. （常用于儿童故事的开头）从前，很久以前
Once upon a time is used to indicate that something happened or existed a long time ago or in an imaginary world. It is often used at the beginning of children's stories.
16. once in a blue moon - see moon
1. on one occasion
e.g. once I ran into her
Synonym: one timein one case
2. at a previous time
e.g. at one time he loved her
her erstwhile writing
she was a dancer once
Synonym: formerlyat one timeerstwhileerst
3. as soon as
e.g. once we are home, we can rest