from用作介词，用来表示做为起点的特定地点或时间，有从...起，从...来，免掉，因为等含义。可用来指定来源、起因、方法或用具。
1.从...起，始于
She is singing from morning to night.她从早唱到晚。
2.从;由
He rose from office boy to managing director in fifteen years.
他十五年里从办公室勤杂员升到总经理。
3.用来表示做为起点的特定地点或时间，
walked home from the station
从家走到车站
4.从...来;出自
He comes from Shanghai.他来自上海。
5.表示去除、免掉、阻止、剥夺等
The pill will relieve you from pain.这药丸将使你免受痛苦。
6.表示区别、比较
He is old enough to know right from wrong.他已长大,能够辨别是非了。
7.由于：用来指定来源、起因、方法或用具：
a note from the teacher
老师写的条
taking a book from the shelf.
从架子上拿本书
