at the time of意思是“在那時”，強調(diào)在某個時間點，后面接名詞或者名詞從句；when意思是“當……時候”，可以在任何時段使用，后面可以接各種從句或者直接接時間。when的使用范圍更廣，也比較常用。

at the time of例句

These prices are correct at the time of going to press.

這些價格在付印時是準確無誤的。

The movie is set at the time of the Russian revolution.

這部電影以俄國革命時期為背景。

We need to establish where she was at the time of the shooting.

我們需要查實槍擊發(fā)生時她在何處。

when的例句

Some people don't know when they're well off.

有些人身在福中不知福。

I didn't use to like him much when we were at school.

以前我們同學時，我并不太喜歡他。

When I left they were all still hard at it.

我離開的時候他們都還在努力工作。