Should/Could

 1. He should take the express. The local arrives too late.

2. They said we could have two aisle seats or an aisle and a window seat.

3. They could buy a ticket at the station or on the train. It doesn´t matter.

4. Which train should we take ? We absolutely have to be there on time.

5. You shouldn´t get a one-way ticket. It´s much more expensive each way.