【题目】A good teacher must be able to help his students learn the subject with great interest ______ he reaches the last minute of the class.
A. when B. unless C. until D. after
在线课程【答案】C
【解析】
试题分析：考查状语从句。句意：一个好老师一定能帮助他的学生带着极大的兴趣学这一门学科，直到他教这一堂课的最后一分钟。故选C。