问题补充:
He commanded the students the classroom before he returned.
A. did not leave
B. leave not
C. not to leave
D. not leaving
答案:
A. did not leave
B. leave not
(答案→)C. not to leave
D. not leaving
解析:考查虚拟语气。句意:他要求学生们在他回来之前不能离开教室 。动词command如果作“要求”解时,后加动词的虚拟语气形式,即should+动词原形。Should可以被省略。故选C。