set about sth./doing sth. 着手做某事。
We set about our task at once with great enthusiasm.
My parents set aside a bit of money every month.我的父母每个月都存点钱。
set off 动身,出发; 燃放(鞭炮等),使..爆炸或发出响声。
After we had finished eating, he proposed to set off immediately.
set out 动身,出发; set out to do sth.打算或着手做某事。
They set out as the sun was rising. 太阳升起时,他们就出发了。
The school has set up a special class to help slow students.