A 1972 agreement between Canada and US reduced the amount of phosphates that municipalities had been allowed to dump into the great lakes.
我认为had been allowed 用法没错啊，发生在reduced之前。之前这些地方被允许的排污量。
为什么要用are allowed 或者 were allowed呢？
我当时觉得Reduced确定了，are allowed就肯定错了，直接排除了这个选项。
谢谢！！！
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发表于 2014-10-9 22:02:52
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