来看两例句 The child was feeding the monkey on/with a banana Cattle feed mostly on grass.牛以草为主食 feed...on/with 意思是“喂...吃.../用...喂...,其中feed和on之间要有一个名词,也就是所“喂”的对象 ,这小孩正在喂猴子吃香蕉,“喂”的对象是猴子,其中主语是the child,谓语是was feeding,宾语是the monkey。而feed on 意思是“以...为主食”,有“靠。。。为生”的意思 。feed sb with sth用某物餵某人。