蓝皮书一道题~~~~~~~~~请帮忙哟

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

a 原来的

b at a cost raising water bills so high that

c at a cost which raises water bills high enough so

d whose cost will raise waterbills so high that

e whose cost will raise waterbills high enough so that

为啥不选b涅~~~~ b介词短语作为壮语不行么。。。

答案是？

我选d

b估计和习惯用法有关

at a cost which

or

at a cost of

开心，我也能做对几道题

在看大全，还有80多页没看呢，

我想知道大全是啥？应该和蓝皮书的题差不多吧，时间有限，选一个就好了呗~~~~是不

是白勇语法全解

370页

还没看完，大概300多页，争取明天看完

刚报名月底的考试

我也快考了。。。我这些在看欧冠。。。。。。

赫赫。。。好歹是假期么。。。