标题: 求助OG第74题 [打印本页] 作者: meckychen 时间: 2009-11-19 15:50 标题: 求助OG第74题 A 1972 agreement between Canada and the United States reduced the amount of phosphates that municipalities are allowed to dump into the Great Lakes.
请问为什么要用现在是are allowed ?作者: sayysong 时间: 2009-11-19 16:10
这个美加两国间的1972协议内容（the amount of phosphates that municipalities are allowed to dump into the Great Lakes）直至今日还在生效，虽然它的效果是已经发生了的(reduced）。