skin-deep 肤浅的，表面的

　　Mike's friendships are just skin-deep. He only cares about himself.

　　Mike和朋友的友情都只是表面上的。他真正关心只有他自己。

　　Her beauty is only skin-deep. Actually, she is very mean.

　　她的美貌只是表面现象。其实她人很刻薄。