花非花，雾非雾， 

A flower, yet not truly a flower; a fog, yet not truly a fog;

夜半来，天明去。

It comes at midnight, and leaves at daybreak.

来如春梦几多时？ 

Coming like a spring dream, how long can it be?

去似朝云无觅处。

Leaving like a morning cloud, nowhere to be found.