此一时彼一时的英文：
[Literal Meaning]
this/one/moment, that/one/moment
That was one situation, and this is another.

[解释]
那是一个时候，现在又是一个时候。表示时间不同，情况有了变化。

[Explanation]
Times have changed.

[例子]
此一时，彼一时。你不要再希望他们能够无私地帮助你了。

[Example]
Times have changed. You should not hope that they will help you so selflessly as before.