在直线段出现（），该处一定存在碎弯、小方向或轨距递减不好。

A、垂直加速度

B、曲率

C、横向加速度

D、轨距变化率

---If you       to my birthday party last Saturday, you would have met Jim.

---I was not in Beijing then, otherwise I       to your party.

A．came; would have come

B．had come; would have come

C．would have come; had come

D．would come; had come