1. 用于序数词前:用在序数词前表示“再一”“又一”。如:
She thanked him a second time.
她再次向他道谢。
Shall I ask her a third time?
我还要问她一次吗?
2. 用于由动词转化来的名词前:表示一次、一番等义(通常与 have, take, make, give 等动词连用)。如:
We’ve already had a try at it.
我们已经试过一下。
I went down to the beach and took a swim.
我到海边去游了游泳。
3. 用于专有名词前:相当于a certain,意为“一个”“某个”。如:
The house next door has been bought by a Mr Jones.
隔壁的房子被一个叫琼斯的先生的人买下了。
4. 用于抽象名词前:使之具体化,表示与该之相关的具体的人或事。如:
He was a success in business.
他事业成功。
It’s a pleasure to talk with you.
同你谈话是件令人愉快的事。