A．Living in a house, department, etc.
B．Thinking or talking for too long about something, especially something unpleasant.
C．Finding something pleasant by accident.
D．Chasing or following someone or something, in order to catch them, attack them, etc.

A．They are appreciating the two pictures about the two forms of transport.
B．They are playing a game.
C．They are arguing about the two forms of transport.
D．They are talking about the advantages and disadvantages of the two forms of transport.