单选题 The problem is that they are unable to communicate effectively in the language ______. public services are offered.
A. in which B. for which C. by which D. of which

【正确答案】 A

【答案解析】本题测试定语从句的引导词。我们把language换成English，更好理解些。English in which public services are offered=English+ public services are offered in English. →English which public services are offered in=English in which public services are offered.故选A。