题目内容:
By the time he retires, Carl______president for 15 years at the university.
A.would be
B.will have been
C.will be
D.has been
参考答案:
答案解析:
By the time he retires, Carl______president for 15 years at the university.
A.would be
B.will have been
C.will be
D.has been