A dark cloud of bees comes swarming out of the hive.

黑压压的一大群蜜蜂从那座蜂巢涌过来。

The only dark cloud on the horizon was that they might have to move house.

唯一的忧虑是他们可能要搬家。

A dark cloud passed over the sky.

一朵乌云从天上掠过。

A dark cloud is a sign of rain.

乌云是降雨的信号。

A dark cloud is a sign of rain.

乌云是降雨的预兆。