drop in后面可以跟on，后接拜访的人，而drop by一般不这么使用另外，drop in含有临时生出主意造访的意思，造访未经事先安排而drop by没有明确这层含义固定搭配：drop in on sb拜访某人。

I thought Id drop in on you while I was passing.我曾想路过时顺便来看看你I dropped in on him on my way home.我在回来的路上趁便去他家看了看。

drop in at意为拜访某地I usually drop in at his place on my way home.我回家时，通常顺便到他那里看看Dont you sometimes drop in at her house?。

你不是有时候会顺便到她家去吗？Please drop in at my office when you happen to be free.如果你碰巧有空的话，请到我的办公室来Shall we drop in at a coffee shop?。

我们顺便去一下咖啡店好吗？

Connies For ladies and gentlemen Drop in at any time!康妮发廊为各位男士女士们服务欢迎随时光临！drop by somewhere拜访某地He dropped by my office this morning.

今天早晨他到我办公室串门来了She just dropped by to see how her son was getting on.她只是顺道来看看儿子过得怎么样She dropped by my office this morning to tell me that she was getting married.。

她今天上午顺道来我办公室告诉我她要结婚了We were just going out when Uncle Sam dropped by.我们正要出去，萨姆叔叔来了She and Danny will drop by later.。

她和丹尼一会儿要来坐坐Drop by sometime.有空儿来坐坐call in at sw拜访某地Ill call in at the chemists on my way home.我回家时顺便要去药店一趟。

I called in at my local on the way home.我回家途中去了我住处附近的酒吧。

I called in at the office on the off chance that you would still be there.我打电话给办公室，想看看你是否可能还在那里call in on sb拜访某人。

call on sb拜访某人I called in on her after work.我下班后顺便拜访了她。

Im going to call on one of my former classmates.我要去看望我的一位老同学。