题目

 No one can stop him , ___ the boy is determined to do something .  A. even if      B. now that    C. once   D. although 答案：C面粉生产车间必须严禁吸烟，主要目的是A.保护工人健康B.避免烟尘杂入面粉C.防止污染环境D.防止发生爆炸