If you know ( ) who knows the answer,please let me know.

If you know ( ) who knows the answer,please let me know. If you-----know the answer,please answer me. If you find the key ,please().A let know me B let me know C Could you tell me who knows the answer,please? If you know anyone else who ____(collect) them,please let me Thanks and please let me know who are you If you love me,please don't let me be the last to know是什么意思? If you _____ busy next week ,please let me know. Please let me know if you have any______questions.A.further if you want to go to ( ),please let me know if anything happens ------ the phone,please let me know. A , If Mr Smith___back,please let me know.