【题目】New discoveries have been made by radio telescopes to solve key physics problems, __________ the largest is FAST.
A. with which B. for which C. of which D. by which
在线课程【答案】C
【解析】考查定语从句。句意：用来解决物理学重大难题的射电望远镜已有新的发现。其中最大的难题是FAST. Problems是先行词，of表示所属关系，表示“其中”。