爆笑英语口语 知根知底

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MP3下载

https://online2.tingclass.net/lesson/shi0529/10000/10343/bxyyky070.mp3

https://image.tingclass.net/statics/js/2012

Language Points

God only knows.

If you know what is good for you

know backwards and forwards=know inside out

He's been teaching physics for 30years,so he knows the subject backwards and forwards.