问题
单项选择题
By the following semester, it is likely that the old professor () on the campus of California University for two decades.
A. will have to be teaching
B. will have been taught
C. will have been teaching
D. will be teaching
答案
参考答案：C
解析：
by the following semester“到下学期”，应用将来完成时态。句中用将来完成进行时，指“到下学期时那位老教授就已经在加利福尼亚大学执教20年了(并且还要继续教下去)。”