Out of a clear sky there were enemies all around them.

突然间，他们的周围全是敌人。

This was a thunderbolt out of a clear sky.

这是晴天霹雳。

And then out of a clear sky one day she informed her mother that undergraduates wearied her.

然后有一天， 在晴朗的天空中， 她告诉她的母亲， 本科生让她厌倦了。