问题补充：
You may your teachers for help when you have problems.
A. turn up
Bturn down
C. turn to
D. turn off
答案：
A. turn up
B. turn down
(答案→)C. turn to
D. turn off
解析：词义辨析题。A. turn up 出现 B. turn down 拒绝 C. turn to 求助于 D. turn off 关掉句意：当你有问题时你可以求助于你的老师。根据语境选C
