题目内容：

关于drop in的用法
drop in 有drop in to do sth吗
eg:Drop in to see us any time.
improper to drop in on him so casually.
drop in on sb
drop by 怎么用

优质解答

drop in on是顺便拜访
没有drop in to do sth,只有drop in to sth 表愿意接受
Drop in to see us any time.任何时间都欢迎我们
drop by 是顺便拜访=drop in on