泡沫灭火剂按生成机理分为（）.
A.空气泡沫和化学泡沫
B.高倍泡沫和低倍泡沫
C.普通泡沫和抗溶性泡沫
参考答案：A
My mother cooks dinner for us every day. We don’t need to do _______ before dinner.
A．anything
B．something
C．nothing
D．any thing
我国旱粮种类很多，主要有哪些？
