check in
phrasal verbcheck in (at…)
to go to a desk in a hotel, an airport, etc. and tell an official there that you have arrived （在旅馆、机场等）登记，报到 Please check in at least an hour before departure. 请至少在飞机起飞前一小时办理登机手续。 We've checked in at the hotel. 我们已经在旅馆登记入住。
check something in
to leave bags or cases with an official to be put on a plane or train 托运（行李）