look in (on sb/at...)
make a short visit to sb´s house/a place 短时间探访某人家或到某处
The doctor will look in again this evening. 今晚医生再来探视.
Why don´t you look in (on me) next time you´re in town? 你下次进城来顺便来串门儿好吗?
I may look in at the party on my way home. 我回家时可能顺便到聚会处看看.