Question

Jack hasn't finished ________ his homework．But now he is busy ________ chess on the Internet．

1. A.
   doing; playing
2. B.
   to do; to play
3. C.
   to do; playing
4. D.
   doing; to play

Answer 1

A
动词finish及结构be busy后都应跟动词-ing形式，不能跟动词不定式。