Betty: Fred, I found out about you and that other girl. How could you do this to me?!
贝蒂: 弗瑞德,我已经知道你背着我和另一个女生交往了!你怎么可以这样子对我?!
FIND OUT ABOUT
Meaning: if you find out about something, you discover a fact or information that you did not know before, often because someone was keeping it secret. 查明,弄清情况Grammar: This phrasal verb needs an object. You can not separate the verb from its particles.