讲解文本：

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。