jump-off

1.They defied him to jump off the bridge.

他们激他跳下桥去。

2.Are you stark raving mad, jumping off a moving train?

你疯了吗？居然从行驶中的火上跳下来。

3.They were very foolhardy to jump off the bus while it was still moving.

"公共汽还未停定他们就跳下了,真是太莽撞了。"