当水和冰的体积相等时，那么 ( )
A．水比冰的体积小
B．水比冰的质量大
C．冰和水的密度相等
D．冰和水的质量相等
参考答案：B
— You smoke heavily, so I think it's hard for you to give up smoking.
— _____, I've made it. [ ]
A. Never mind
B. Take your time
C. That's all right
D. Believe it or not
杂质半导体中（）的浓度对温度敏感。
A.少子
B.多子
C.杂质离子
D.空穴
