Question

.The engineer ______my father works is about 50 years old.

to whom B. on whom C. with which D. with whom

Answer 1

D 跟我爸爸一起工作的工程师大约50岁
后面是一个定语从句，完整的应该是my father works with (the engineer), 所以就是with whom

Answer 2

D. with whom 和我父亲一起工作的工程师大约50岁了