来自VOA的[ Ask a Teacher ] Drop By and Drop In (2021/10/1) 节选
有个人问我“drop in”（临时起意的顺道拜访）和“drop by”（没有明确说明是顺便去拜访还是事先安排好的要去拜访）之间的区别，这里我们就借用VOA的一篇学习文章来解答一下。
Both of these expressions mean to pay someone or something an informal visit.
解答：
这两个短语都是可以用来表示非正式拜访某人或者某事。
看到了吗？VOA权威说了两者都是非正式拜访的意思。
一、Drop By
1、It is a two-part phrasal verb, which means it combines a verb and an adverb. The verb is "drop," which usually describes something falling in small amounts. The adverb is "by" which means "near."
解答：
Drop by是一个由两部分组成的短语动词，结合了动词和副词。动词是drop，通常描述的是少量掉落的东西；副词是by，意思是near（附近）。
Drop by的字面意思是掉在附近，但我们一般只使用其引申含义：顺道拜访。
例：
I asked James to drop by the coffee house tonight to hear our music.
我邀请詹姆斯今晚顺道去咖啡馆听我们的音乐。
在本例中，你去咖啡馆并不需要邀请函，你可以进去待一会，甚至呆在馆外不进去，依旧可以说你“顺道拜访”了。
见面打个招呼就可以用Drop By了，没必要进去拜访的地方
2、I found that people are using "drop by" to talk about the places they visit on a computer, as well as in person. Here are some examples:
（1）Please drop by my other blog on photography.
请访问我的另一个摄影博客。
（2）Drop by every Monday for a new Mainly about Boats column.
每周一顺道来看一下新专栏——Mainly about Boats
解答：
人们经常用“drop by”来讨论他们在电脑上访问或者亲自去的地方。访问某某网站用drop by是一个常用的用法。
浏览某个网址可以用drop by WWW.XXXXX
二、Drop In
1、Next, we can look at "drop in." This expression can be a two or three-word phrasal verb. The two-word form, "drop in," can be used like "drop by" with one difference – if you go to a place and plan to enter it, you would say:
I was passing your street and thought I'd drop in – do you have time for tea?
我路过你家那条街道，想顺便来看看——你有时间喝茶吗？
If you did not plan to enter the house or building, you could use "drop by, as in:
I will drop by tomorrow and put the letter under your door.
如果你不打算进去该房屋或者建筑物，你可以用drop by。如：我明天会顺道过来，把信放你家门下。
解答：
Drop in的动词短语有两种形式，一种是drop in另一种是drop in on。如果你要拜访人家家里，确实要进入屋内，那你预约或者说明的时候一定要用drop in。
去人家家里要用Drop In
三、Drop In on someone
The three-word phrasal verb form is "drop in on." You might hear it used this way: Every now and then he would drop in on Grandmother for a quick chat.
他每隔一段时间就会顺道拜访祖母，简短地聊一下。
You can tell from this final example that we use "drop in on" when we are talking about entering someone's home:
The middle of the night is a bad time to drop in on a friend, but we could see that Megan needed help.
半晚去拜访朋友并不好，但是我们看出来梅根需要帮忙。
解答：
Drop in on+someone是固定用法，表示拜访某人，至于地点无所谓