The engineer my father works is about 60 years old.
A. to whom
B. on whom
C. with whom
D. with which
网友回答
A. to whom
B. on whom
(答案→)C. with whom
D. with which
解析：句意：这个我父亲与之一起工作的工程师大约60岁了。这个句子中含有一个定语从句，work with sb.是固定用法，意思是与某人一起工作，且关系词指人，故用with whom，选C。