问题
选择题
Please don’t stand up in class _____ you ______.
A．until ; are told to
B．when ; are told
C．after ; were told
D．before ; were told to
答案
答案：A
题目分析：句意：在课堂上请到允许你时再站立。Not···until直到……才，是一固定句型；主句使用一般现在时，故时间从句也用一般现在时。Tell sb to do sth告诉某人做某事，改为被动语态后不可丢掉不懂事标记to。所以选A。