The professor you referred to in the letter us students three lectures by next Monday.
A. has given
B. will given
C. will have given
D. Gave
网友回答
A. has given
B. will given
(答案→)C. will have given
D. Gave
解析：考查时态。you referred to in the letter是定语从句，省略了who/that，by next Monday到下周，by+将来的时间，与将来完成时连用。句意：你在信里提到的那位教授到下周，将已经给我们学生做过三次讲座了。故选C。