A：油着火，用水浇灭
B：电器着火，用泡沫灭火器浇灭
C：用明火检查液化气罐是否漏气
D：在火场的浓烟中逃生，可用湿毛巾捂住口鼻，低姿势前行
地球上最大的生态系统是（ ）
蚊、蝇等害虫对DDT产生抗药性的主要原因是 （ ）
— Thanks for listening to my problem and giving me your advice, Amy.
— _________. That's what friends are for.
— What do you think of your teacher?
— He is very kind. He always the students his own children.
