A、  B、  C、  D、  C图中的人们正骑在山地自行车上。(A)中的race有干扰作用，但watch the race是“观看比赛”的意思，因此(A)错误。(D)中的get on bicycles是“骑到车上”

(A) He is walking down the corridor.
(B) He is entering the room.
(C) He is wiping the hallway with a mop.
(D) He is sitting on the floor.

(A) They are watching the race.
(B) They are parking their bikes.
(C) They are riding bikes over rocks.
(D) They are getting on bicycles.