水中所含氯以氯胶存在时，称为自由性氯。
参考答案：错
Many people think that I'm a lucky dog, but it takes me years of hard work to be _______ I am now. [ ]
A. what
B. which
C. whom
D. how
下列绝热材料中，宜做保冷绝热又能防火的绝热材料是（）。
A.岩棉
B.矿渣棉
C.玻璃棉
D.泡沫玻璃
