一个两位数，个位上的数字是a，十位上的数字是b，交换这个两位数个位上与十位上数的位置，得到新的两位数，这两个两位数的和是（ ）．
11a+11b
有两个点电荷q1、q2，放在真空中两点，已知q1=3q2，则q1对q2静电力跟q2对q1静电力之比为（ ）
A．1：3
B．1：1
C．3：1
D．无法确定
—Did you hear about the air crash? I feel so lucky!
—Yes．If you _____ that flight, I _____ speaking to you now．
A．were taking; wouldn't be
B．took; wouldn't have been
C．had taken; wouldn't be
D．had taken; wouldn't have been
