OG11-62，动词时态

fiestaxie

62. 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

正确答案选D。

OG的解释是：

An agreement that occurred in 1972 is correctly described with the past tense verb reduced. Since the dumping continues into the present, the past perfect verb had been allowed should instead be the present are allowed.

我怎么也想不通的是，既然agreement是1972年发生的，而且用一般过去时表示了它的动作reduced。agreement已经发生了reduced amount的作用，为啥那个dumping是持续到现在，要用现在时呢？

想不通啊想不通

fiestaxie

看了gemj的大全，上边的标准答案居然选的是A???

到底哪个才是标准答案啊？

虽然我肯定偏向A。。。

sbcdsbcd

A,D的语法都ok. 但是从意思上看 A就有问题了。
过去完成时必须有另外一个过去动作作参照，一眼看去似乎reduced正合适，但had been dumped须发生在reduced之前，那么句子意思则是：这个agreement 减少了过去dumped的量。这是不合逻辑的，过去dumped 的量是不能被后来签订的agreement所减少的。agreement只能影响其签订之后的量。

kiwifoodtown

这个问题经常会被问到，这里为什么要选D，因为that municipalities are allowed to dump作为定语从句，仅仅限定修饰了phosphates。所以，这里只用了一般现在时。而reduced作为主谓语，对amount 起作用，针对1972，用了过去时。很多人不理解为什么要在从句用一般现在时，就是因为误认为that municipalities are allowed to dump是修饰整个the amount of phosphates，所以思维上转不过来。