A good teacher must be able to hold his students’ attention he reaches the end of the class.
A. when
B. after
C. until
D. unless
网友回答
A. when
B. after
(答案→)C. until
D. unless
解析：考查连词辨析。A当…时；B在…后；C直到…才；D除非；句意：好的老师一定能够吸引教师的注意力，直到这节课结束。本句中前面句子的谓语动词hold his students’ attention是一个延续性动词，如果是短暂性动词，则使用not…until…；故C正确。