make a mountain out of a molehill字面意思把小土堆说成大山，引申为小题大做；大惊小怪。

【例句】
There are so many things which are simple, but someone always wants to make a mountain out of a molehill.
其实很多事情都很简单，但是有些人就会小题大做。

You are not hurt badly. Stop trying to make a mountain out of a molehill with crying.
你的伤并不重，不要小题大做，这么放声大哭。