A:醋易挥发
B:分子是不断运动的
C:分子可以再分
D:分子的体积很小肉眼看不见
—________ did you stay there?
—I stayed there for two hours.
已知圆C1:(x﹣a)2+(y+2)2=4与圆C2:(x+b)2+(y+2)2=1相外切,则ab的最大值为( )
Do you make any ____ (friend) here?