GWD20-15，已经搜过啦，米有>_<

Q15:

The city has proposed a number of water treatment and conservation projects the cost of which raises water bills high enough so that even environmentalists are beginning to raise alarms.

1. the cost of which raises water bills high enough so that
2. at a cost raising water bills so high that
3. at a cost which raises water bills high enough so
4. whose cost will raise water bills so high that
5. whose cost will raise water bills high enough so that

正确答案选D，不是很懂为什么D对，那个whose的指代米有问题么？偶选了B……

whose修饰projects,因为里面的cost是复数形式，因此不能指代The city。water treatment and conservation 是修饰projects的，因此也不会指代到，所以指代没问题。

这道题只有可能B和D是对的，其他的错误都比较明显。d的从句中用了will，表示projects即将带来但目前还没带来的东西。raising water 强调的是正在发生的一个状态，所以用从句好了

回去查的时候赫然发现自己把套数弄错了…………我这个脑子不顶事的笨蛋

谢谢楼上两位，yaoshuming亲解释的超级详细的说～^_^