题目内容：

More amd more people have realised we won't have cleaner water to drink unless something _____ soon
A.was done B.will be done C.to be done D.is done
请详细讲讲,另外,be done在这里是什么意思

优质解答

答案是D
unless引导条件状语从句
相当于if not
if something is not done soon如果不及时采取措施
A过去时不对,B不用将来时,因为这是条件状语从句
C不能充当从句谓语
be done是“被做”的意思,表示被动的.