-- Not bad, we're having a great time. Thank you.
A:What are you doing?
B:How's the weather in Beijing?
C:How do you get to school?
D:How's it going?
一汽车在路面情况相同的公路上直线行驶,下面关于车速、惯性、质量和滑行路程的讨论正确的是( )