请教 og 62 （11th edition)

A 1972 agreement between Canada and the United States reduced the amount of phosphates

that minicipalities had been allowed to dump into the Great Lakes.

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

(B) reduced the phosphate amount that municipalities have been allowed to dump

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

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

答案是C,可是我不理解定语从句中“municipalities are allowed to dump”的用法。应该是phosphates被允许dump,

而这个从句用被动语态让我觉得是municipalities 被允许dump 。如果答案改成“reduced the amount of phosphates allowed to dump by municipalities" ，我觉得才是正确语意。不知道是不是我理解有误，请教各位。谢谢。

同问

同意楼上的，是自制的政府或区域被允许这么做，所以是sb.be allowed to do sth.

而题目设计到的是颁布的法律法规，所以用一般现在时

a呢，为什么要用一般现在时态，不用过去完成时

1.       
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（A）

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

OG上的解释说是因为allowed to dump这一动作仍然在延续，所以用are allowed to dump.

但我觉得句中似乎没有可以指明这一动作延续的地方，反而A选项更好一些，allowed to dump发生在 agreement 之后，而that municipalities had been allowed to dump into the Great Lakes修饰the amount of phosphates ，而非phosphates。也就是说虽然phosphates仍然are allowed to dump，但the amount of phosphates 却已经改变了。不知道大家有什么想法？

顺便提下，OG11的解释很多都很不明了，我看了3遍还有不少没看懂，个人建议还是少用，可惜我已经晚了，下月11号考试。

这题的时态的确是诡异了些，颠覆了从小学习的关于时态搭配的规则……

不过我感觉OG还是要多看的，不管他们的解释多不讲道理，毕竟话语权在他们手里……

而且，个人的感觉，很多解释还是蛮有道理的说，从中可以看出他们的思路，关于这点，以前不少人也说过了。