travel的过去式和过去分词

双语例句：

Sound travels better in water than in air.

声音在水中比在空气中传播得快。

I've always had a yen to travel around the world.

我一直非常渴望周游世界。

I go to bed early if I'm travelling the next day.

如果第二天去旅行我就早睡。

Flying is quite the best way to travel.

航空绝对是最佳旅行方式。

When I finished college I went travelling for six months.

我大学毕业后在外旅行了六个月。

We lost our money when the travel company went bust.

旅行社破产，我们的钱都赔了进去。