问题描述：
选什么,为什么?
if you have never kept any pets,you will not be able to know the pleasure of watching the pet you have kept （）.
A.play B.to play C.played D.playing
if you have never kept any pets,you will not be able to know the pleasure of watching the pet you have kept （）.
A.play B.to play C.played D.playing
问题解答：
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