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general::
Phrase(s): What’s (there) to know?
Inf. This doesn’t require any special knowledge, so what are you talking about? • Bill: Do you know how to wind a watch? Bob: Wind a watch? What’s there to know? • Sue: We must find someone who knows how to repair a broken lawnmower. Tom: What’s to know? Just a little tightening here and there. That’s all it needs.
McGrawhill's American Idioms And Phrasal Verbs