All his free time is _____ by charity work, but he feels it meaningful.

A．put up

B．given up

C．picked up

D．taken up

有人从列车上坠下或线路内有人死伤（特快旅客列车部危及本列车运行安全时除外），危及行车和人身安全情形时，应使用（）停车。