第6题: [单项选择]Six months ago the World Health Organization recommended that cigarette smoking and the use of plywood and particle board ______ in enclosed areas. A. be restricted B. should restrict C. will be restricted D. must be restricted 参考答案:A 答案解析:recommend后接的宾语从句要使用虚拟语气“should do...”,should还可以省略掉。