It's a long time since they left.

　　他們已經(jīng)離開很久了。

　　Come on, it's time we left.

　　快點(diǎn)，我們該走了。

　　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。

　　It's not for me to say why he left.

　　不適宜由我說出他離開的原因。

　　The university is on the left bank of the river.

　　大學(xué)在河的左岸。