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 （D）

(E) reduces the amount of phosphates allowed for dumping by municipalities

(C) reduces the phosphate amount municipalities have been allowed to dump

(D) reduced the amount of phosphates that municipalities are allowed to dump （D）

(E) reduces the amount of phosphates allowed for dumping by municipalities

不知道你要问什么，就给你分析一下时态吧？

(A) reduced the amount of phosphates that municipalities had been allowed to dump

过去完成时态，动作发生在过去的过去，也就是1972年还要以前的日子。那意思就是市政府在1972年之前就允许倒 phosphates 拉，

(B) reduced the phosphate amount that municipalities had been dumping

过去完成进行时态就是动作发生在过去的过去，但在过去的那个时间点还在发生，并有可能延续到过去将来，也就是1972年还要以前的日子就同意拉，但1972年还在进行，1972年之后还有可能进行下去。

(C) reduces the phosphate amount municipalities have been allowed to dump

现在完成时态，动作发生在过去对现在有影响。1972年就同意拉，对现在有了影响。

(D) reduced the amount of phosphates that municipalities are allowed to dump

一般式的被动形式。不用多少拉。

(E) reduces the amount of phosphates allowed for dumping by municipalities

非谓语拉，不是时态问题。