乐极生悲的英文：
[Literal Meaning]
joy/extreme/generate/sorrow
Extreme joy begets sorrow.

[解释]
高兴到极点时，发生使人悲伤的事。

[Explanation]
Extreme joy begets sorrow.

[例子]
你看看，是不是乐极生悲，忘了把中了大奖的彩票放在哪里了。

[Example]
Look, isn't it extreme joy begets sorrow? You forgot where you put the lottery ticket which won a big prize.

After joy comes sadness
乐极生悲

Too great pleasure will bring about sadness．
乐极生悲

Sadness and gladness succeed one another.
乐极生悲，苦尽甘来