根据产生矿尘的来源可分为（）。
A、原生矿尘
B、沉积矿尘
C、浮游矿尘
D、次生矿尘
参考答案：A, D
It's _____ problem _____ we can't work it out.[ ]
A. so confused a; that
B. such a confusing; that
C. such confusing a; so that
D. so a confused; so that
下述哪个决定了血红蛋白氧饱和度的大小
A．血红蛋白浓度B．2,3-DPG含量C．pHD．氧分压
