C
by是指方式,方法,还可用于被动语态,by sb,
例句,This composition is written by me.
You can learn English by listening to the tape.
with中文是“和”,表示有,附带着,伴随with sb/sth
例句,I am in love with you.I can kill you with this gun.
是的,都可表示方式,区别上来说不大,我觉得主要找语感,读起来顺不顺.例如：The table is covered with/by a piece of cloth.就都可用,
作为介词,with常指跟,和一起
by还有经过,靠近,在一旁,有时有通过,由的意思
还可用于时间,表示到.之前,
我觉得还有一个较常用的意思,就是根据,按照