A:(a+3)(a﹣3)=a2﹣9
B:x2+x﹣5=(x﹣2)(x+3)+1
C:a2b+ab2=ab(a+b)
D:x2+1=x(x+ 1x )
- Would you like to play basketball with us this afternoon?
- ________, but my mother is ill.
—_______
如图所示,带电量之比为qA:qB=1:3的带电粒子A,B,先后以相同的速度从同一点射入平行板电容器中,不计重力,带电粒子偏转后打在同一极板上,水平飞行距离之比为XA:XB=2:1,则带电粒子的质量之比mA:mB以及在电场中飞行时间之比tA:tB分别为( )