爆炸极限指的是遇明火发生爆炸的可燃混合气体中，可燃成分的（）。
A.容积浓度范围
B.质量浓度范围
C.容积浓度最高值
D.质量浓度最高值
参考答案：A
单词拼写（共5小题；每小题1分，满分5分）
小题1:The Song Dynasty c______________ three great inventions to world civilization, which have improved people’s life a lot.
小题2:A kind of friendly ____________ (气氛) can be felt throughout the conversation.
小题3:You have been ______________ (推荐) as a typist in our company.
小题4:He lit a c_________________, got up and went off.
小题5: Doing sports r___________ will help you keep healthy.
多宿主蜱
