Dont sell that man short 不要小瞧他
sell that man short这个短语的意思很像中国俗语把人瞧扁了，也就是没看到某人的长处。所以sell someone short意思就是小看某人。
例句:
Dont sell that man short. Hes one of the smartest lawyers in town. Youd be wise to hire him if youre in trouble - he seldom loses a case.
这段话说：可别小看了这个人。他是城里最能干的律师之一。你要有麻烦找他才对，