OG12-74时态问题

cckjenius

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

主句是过去时态recuded，从句为什么可以用一般现在时啊are allowed，这到底是什么道理？？？？

seuhongkai

可以用现在时也可以用过去时，现在时表示这个agreement现在还有效，过去时表示现在已经没有效了，只是不能用过去完成时

cckjenius

我记得高中老师说主句用过去时，从句绝对不会用现在时，只能是过去时。
而主句是现在时，从句可以用过去时。
老师是这么讲的不？？？

banglixing

高中老师讲得太绝对，而且其实主要针对的是宾语从句，如I told her that her dad

was angery.但是内容是一些实验结果，普遍原理的时候还是用一般现在时。
定语从句是没有这种限制的，因为从句的内容只跟修饰的词相关，跟主语的内容无关，故

主句时态没有影响。

cckjenius

精彩精彩，比我老师讲的好多了，感谢