问题补充:
Living in the mountain area has its problems, obtaining water is a big problem.
A. of which
B. for what
C. as
D. whose
答案:
(答案→)A. of which
B. for what
C. as
D. whose
解析:考查非限制性定语从句。句意:居住在山区有许多问题,找到水源就是其中一个很大的难题。what不用于定语从句,whose作定语,后常跟一个名词,排除B、D;as引导非限制性定语从句,作主语或宾语,这里不缺少成分,排除C;obtaining water和problems是从属关系,应该用of which引导定语从句,故选A。