He manded the students the classroom before he returned.
A. did not leave
B. leave not
C. not to leave
D. not leaving
网友回答
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mand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。