A．Report the incident to the police.
B．Wait for the person who had taken his suitcase to come back.
C．Try to contact the taxi driver.
D．Report the incident to the Railway Information desk.

A．There was no garbage left to clean up.
B．There was more garbage than before and they had to work harder.
C．The fiver had become so clean that a lot of water-birds came back.
D．The river was much cleaner and they had to search for garbage.