set out/set about/set down 区别在哪?

set out/set about/set down 区别在哪?
set out/set about/set down 区别在哪?

set out/set about/set down 区别在哪?
set out
出发
v.规划,展现
v.出发,开始
set about
开始,着手
set down
1太阳落山
2n.申斥(搭乘,触地)飞机着陆