check in
1．register in a hotel；report one's arrival 在旅馆登记住宿；报到；签到
Have you checked in at the hotel yet？你在旅馆登记住宿了吗？
We have to check in at the office building at 8．我们必须在8点到办公楼签到。
The friends we had invited did not check in until Saturday．我们邀请的朋友直到星期六才到达。
2．receive sth．back and make a record of it 收回；注消；收到登记
I put the books on the library desk，and the librarian checked them in．我把书放在图书馆的柜台上，图书管理员验收了这些书。
We're supposed to check our luggage in before 8：00．我们应在8点钟前交运行李。
You can check your suitcases in at the desk．你们可以把箱子寄存在服务台。