They checked in at that hotel.

他们在那家旅馆登记入住了。

He had checked in at HongQiao airport for a flight to New York.

他在虹桥机场办理了飞往纽约的登机手续。

A:Good evening,sir,can I help you?

晚上好先生，我能为您效劳吗?

B:Yes,I'd like to check in,please.

是的，我要办理入住登记。

Ao you have a reservation?

您预定房间了吗?

B:Yes,my name is Jack.I have a reservation for three nights.

是的，我叫杰克，我预定了三个晚上的房间。