og 74

glw1900

A 1972 agreement between Canada and the United States reduced the amount of phosphates that municipalities had been allowed to dump into the Great Lakes.
(A)    reduced the amount of phosphates that municipalities had been allowed to dump
(B)    reduced the phosphate amount that municipalities had been dumping
(C)    reduces the phosphate amount municipalities have been allowed to dump
(D)    reduced the amount of phosphates that municipalities are allowed to dump
(E)    reduces the amount of phosphates allowed for dumping by municipalities
答案为D
我想问问为什么a的过去完成时不行呢，那个municipalities   allowed应该是在那个协议之前呀，就是过去的过去么，为什么不是过去完成时呢
求回答

donkid

不行，因为达成协议之后，这个标准就下降了，而且沿用带现在，也就是现在也还是这个标准。换句话说，是1972年的一份协议促成了一个现在发生的结果，因此要用一般现在时。

glw1900

谢谢谢谢，我想明白了，的确是。。。。