1. at that time

2. when

3. then

Examples:

1. 他找到一份在国外的工作, 他们的婚姻就在那时开始出现问题.

Their marriage started to go wrong when he got a job abroad.

2. 就在那时我产生了逃跑的念头.

It was then that I conceived the notion of running away.

3. 正在那时候，我想到一个妙主意。

Just then a bright idea occurred to me.

4. 正在那时，女主人迅速带我到别的地方去见其他的一些客人。

Just then, our hostess whirled me away to meet some of the other guests.

5. 就在那时电话铃响了.

At that (very) moment, the phone rang.

6.到那时止,在那时以前

till then

7.在那时以前,我对这事一无所知。

Until then, I knew nothing at all about it.

8.正在那时，老师进来了。

Just then, our teacher came in.