______ many times,none of the boys dared swim in that river______ many times,none of the boys dared swim in that river.A.Having warned B.Been warned C.Having warning D.Having been warned

问题描述:

______ many times,none of the boys dared swim in that river
______ many times,none of the boys dared swim in that river.
A.Having warned B.Been warned C.Having warning D.Having been warned

D.Having been warned