Question

--Why does the lake smell terrible?
-- Because a large amount of water_______.

A．have polluted	B．is being polluted
C．has been polluted	D．have been polluted

Answer 1

C 

试题分析：句意：--为什么这个湖这么难闻？--因为很多水已经被污染了。a large amount of+不可数名词做主语的时候，谓语是单数，如果是large amounts of+不可数名词做主语的时候，谓语是复数，所以排除AD，而且从Why does the lake smell terrible?可知这个湖已经被污染了，所以选C。