The scientists have made an exhaustive study of the virus many people have been inflected.
A. to which
B. in which
C. with which
D. for which
网友回答
A. to which
B. in which
(答案→)C. with which
D. for which
解析：句意：科学家对许多人已经感染的病毒做出了详尽的研究。这里使用了定语从句，先行词是the virus，定语从句中使用了词组be infected with，所以缺少介词with和关系代词which，选C。