问题
选择题
Our playground is not so tidy and beautiful as before. Students must _____ dirty things on it.
A. be stopped to throw
B. be stopped from throwing
C. stop to throw
答案
答案：B
题目分析：句意：我们的操场不如以前干净和美丽了，学生们必须禁止向上面扔脏东西。“禁止某人做某事”是“stop sb. from doing sth.”,根据题干分析应是学生被禁止，所以用被动语态，故选B。