旅客在中转站和列车上可要求变更（），必须在客票有效期内能够到达到站时方可办理。

A.径路

B.座别

C.铺别

D.越站

If one 　　　　 succeed， one must put his heart into his career.

A．will

B．is going to

C．is to

D．is about to