小题大做：夸大事情的重要性或严重性。
Making a mountain out of a molehill is an idiom referring to over-reactive, histrionic behaviour where a person makes too much of a minor issue. It seems to have come into existence in the 16th century.
小题大作；言过其实
I'm tired of listening to John make a mountain out of a molehill.
我受不了约翰的小题大做，他不断抱怨一些不要的事。
You're not hurt badly. Stop trying to make a mountain out of a molehill with crying.
你伤得并不重，不要大惊小怪地嚷嚷，小题大做了。
Your "broken arm" was only a sprained wrist. Don't make a mountain out of a molehill.
你只是扭了一下手腕，哪有摔断胳膊。别小题大做了。