21. My father is _________very calm person, but my mother is just ________opposite.
A. a, an B. a, the C. 不填，an D.不填, the
22. ----T he last one_______ pays the meal.
--- Agreed!
A. arrived B. arrives C. to arrive D. arriving
23. The children went home from school, their homework _______ for the day.
A. finishing B. finished C. had been finished D. were finished
