一、词义不同1、call on 指访问,拜访;号召,请求。2、call for指要求;需要;提倡;邀请;为…叫喊。3、call in 召集、召来,通常指叫来帮忙。4、call up 打电话、想起。二、用法不同1、Call on 表示拜访、访问,call on后接表示人的名词或代词。如:I called on the Smiths yesterday.我昨天拜访了史密斯一家人。2、call for表示“需要;要求”。for后接名词,表示需要、要求的对象。如:The negotiations will call for considerable dexterity. (call for指需要)进行这些谈判需要相当圆滑的手腕。They called for a radical reform of our tax system. (call for指要求)他们要求对税收制度进行根本改革。3、Call in 请来、找来、召来解,请人来作某种专业的咨询或帮忙的意思,如call in a doctor找医生等。如:Your father is ill, you should call in a doctor at once.你父亲病了,应该马上去请个大夫来。The police have been called in to help make it clear.已请来了警察帮忙把这件事弄清楚。4、call up主要表示打电话;使想起;征召。表示打电话时,后面接打过去电话的人。表示想起时,后面可以接回忆的情景。如:She called up a friend just for a chat. 她打电话给一个朋友,只是要聊聊天。She can still call up scenes of childhood. 她仍能想起儿时的情景。He was called up at the beginning of the war. 战争开始时他就被征召入伍了。