问题补充：
—Would you like to climb mountains with me this Sunday?
—I’d love to. But I play table tennis against Class Three.
A. am going
B. am going to
C. am
D. going to
答案：
A. am going
(答案→)B. am going to
C. am
D. going to
解析：根据上文时间状语可知下文说的是将来发生的动作，be + going +to+do，表示将来发生的动作。故选B.
