问题补充：
The quality of the teachers will influence the students,and , the quality of the students will influence the teachers.
A. as a result
B. in vain
C. in turn
D. in time
答案：
A. as a result
B. in vain
(答案→)C. in turn
D. in time
解析：短语辨析。A. 结果是 B.徒然；无效 C.轮流；依次 D. 及时；适时。句意：教师的素质会影响到学生，并且反过来，学生的素质也会影响到老师。故选C。
