问题补充:
Stay awake! You should know that it to sleep in class.
A. doesn’t permit
B. is not permitted
C. will not be permitted
D. was not permitted
答案:
A. doesn’t permit
(答案→)B. is not permitted
C. will not be permitted
D. was not permitted
解析:句意:保持清醒,你应该知道在课堂上是不允许睡觉的。这里it是形式主语,to sleep in class是真正的主语,根据Stay awake可知说的现在不能睡觉,所以应该用现在时故选B。