[em:70]OG-12-74 C选项have been allowed to dump~~欢迎讨论

靓linda

看了好多帖子，大都围绕A选项讨论,我。。。我。。选的是C选项。。还是不明白为什么have been allowed 不对呢？？求牛牛解答。。
Og 12-74.    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

靓linda

不好意思......我还是有疑惑
og 解释说用are allowed， if the agreement remained in effect  when sentence was written......我觉得这样子的话为什么不能用have been allowed 呢？have been allowed 不也是remained in effect when sentence was written????

首先主语用过去语态，have就不对了。现在完成时（Present perfect）过去发生并且已经完成的动作对现在造成影响或后果，过去某一时间开始并一直持续到现在并且有可能还会持续的动作或状态。

其实还是语感问题，have been在这里就是不对。很难说为啥

-- by 会员 pinkking (2012/8/5 9:09:08)

pinkking

首先主语用过去语态，have就不对了。现在完成时（Present perfect）过去发生并且已经完成的动作对现在造成影响或后果，过去某一时间开始并一直持续到现在并且有可能还会持续的动作或状态。

其实还是语感问题，have been在这里就是不对。很难说为啥