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 throwing
C．stop to throw
D．stop from throwing
答案
答案：B
题目分析：句意：我们的操场不如以前干净整洁，必须阻止学生乱丢杂物。Stop to do sth停下来去做某事；stop doing sth停止做某事；stop sb from doing sth阻止某人做某事。结合句意必须阻止学生乱丢杂物，而学生students作句子主语，故用被动语态。所以选B。