Don’t judge a book by its cover.不能以貌取人，人不可貌相；不能通过表面来判断事物的好坏。可以指人，也可指物。

judge 判断；评判

cover 覆盖；封面

This machine may not be eye-catching ,but don’t judge a book by its cover, I promise you will be amazed after you see what it can do.这个机器可能看起来很不起眼，但是我们不能仅从表面来评判事物好坏，我保证你看到它功能后你会被惊艳到的。

I know she’s a little frumpy, but as they say, you can’t judge a book by the cover, she actually is a very talented girl.我知道她有点邋遢，但是，俗话说人不可貌相，她其实是个很有才的女孩。