问题描述：
大家给翻译下这句话吧,谢谢
then what could be more important than purifying the water your family drinks?
顺便讲讲语法,为什么要用COULD BE
then what could be more important than purifying the water your family drinks?
顺便讲讲语法,为什么要用COULD BE
问题解答：
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