Q21:

Medicare, the United States government’s health insurance program for the elderly and disabled, covers the full cost of home health care, but not with other nonhospital services where 20 percent of the costs must be paid by beneficiaries.

1. but not with other nonhospital services where 20 percent of the costs must be paid by beneficiaries
2. but not of other nonhospital services, making beneficiaries pay 20 percent of the costs
3. but not of other nonhospital services, for which beneficiaries must pay 20 percent of the costs
4. which is unlike other nonhospital services in that 20 percent of the costs must be paid by beneficiaries
5. which is unlike other nonhospital services that make beneficiaries pay 20 percent of the costs

答案是选c,为什么b不行,c更好在哪里?请指教!

thanks a lot 明白多了，不过有个地方还是有点迷惑,形如a do b,doing(或者done..)....,这个doing(done)一定是修饰a的么,可不可以理解为修饰b.

操作得实际点如果可以判断出doing or done的动作发出者是b,在选项同时出现doing,done和非限制性从句三个选项哪个是优先考虑的呢.最近作题好象遇到这种问题的还是不少的...还有一些到底是从句修饰还是doing或者done简单修饰..叫人模拟两可,也没有找到讲这方面比较清楚的资料,如果有的话,大家帮忙建议一些...如果在这里能简单串讲一下这几个知识点,真的是不甚感激!!!