大家给翻译下这句话吧,谢谢

供参考
如果改一下
then what is more important than purifying the water (what) your family drinks?
意思就是：那么什么东西比净化家庭饮用水更重要呢?
而原句
then what could be more important than purifying the water your family drinks?
意思是：那么什么东西“能够”比净化家庭饮用水更重要呢?
对比下两个句子,这里的助词 could 表示可能性,而加了could以后 is变成原型be。