请问set out、set about、set off各是什么意思，你能为我造句子吗

set out出发

They set out on the last stage of their journey.
他们开始了旅行的最后一程.
She set out at dawn.
她天一亮就动身了.

set about: 开始,着手

1. You must set about your work at once.
你必须立即开始工作。
2. Do you know how to set about going on this work?
你知道怎样着手进行这项工作吗？

set off=set out出发

If you want to catch that train we'd better set off for the station immediately.
你要是想赶上那班火车，咱们就最好马上动身去火车站。
What time are you planning to set off tomorrow?
你打算明天几点钟启程?

楼上的各位已经把意思说清楚了，如果你是为了做题的话，还有要注意的地方,因为考试能用到的区别主要是“开始”：
1.set out+ to do sth.
2.set about+ doing sth.
3.set out (for),set off (for)都可以表示：动身/赴………另外head for,leave for 也是这个意思。

They set out to do their homework.
We'd better set off for the station if we want to catch the train.
She set about cleaning her bedroom.

set about:
开始,着手；攻击
As soon as she arrived she set about tidying up the room.她一到，就开始收拾房间。
The little fellow rolled up his sleeves and set about the bully.小家伙卷起他的袖子向暴徒进攻。
set off:
动身，出发；引起；装饰，点缀；使...爆发
We will set off for the factory tomorrow.我们明天打算去工厂。
set out:
动身，出发；打算，企图；表达，发表
The boys plan to set out for Tianjin next week.
孩子们计划下星期动身去天津。