Think about it. That little boy who's running back into his house, he may have a nice, clean fresh water supply, but he's got dirty hands that he's going to contaminate his water supply with.
想想看吧。那个小男孩儿， 他跑着回到家里， 他可能有很好，很干净的给水设备， 但是他的赃手会污染给水设备。