问题补充：
Food safety is important. Rules to stop people from food pollution.
A. must make
B. must be made
C. can’t make
D. can’t be made
答案：
A. must make
B. must be made
(答案→)C. can’t make
D. can’t be made
解析：被动语态的用法。 本句句意：食品安全很重要，必须制定制度来阻止人们遭受食品污染；根据句意应该含情态动词must的被动语态，即must be done。
