9、Mathematics ________ study or science of numbers.

24. He is not seriously ill, only a()headache.

23. I’d like the teacher()classes are very interesting and creative..

22. I didn’t expect you to turn()at the meeting yesterday.

21. We worked hard and completed the task().

20. Once environmental damage(), it takes many years for the system to recover.

19. The red flower goes from one to()in the class

18. Two days is not enough for him to finish the work. He needs()day.

17. Therefore, other things()equal, the member of workers that employers want decreases.

16. It’s time we()the lecture because everybody has arrived.

15. The girl is()of a film star.