19. It is known to all ___________ lights travels in straight lines.

18. It seemed _________ he had got the news.

17. It is still a question __________ we shall have our sports meeting ________ the students are looking forward to.

16. ________ is no wonder that he loves English so much so ________ is no need for you to worry about his English learning.

15. It is necessary ________ you should learn some useful sentence patterns by heart.

14. The text mainly tells something about __________ students should serf the internet.

13. I read about it in some book or other. Does it matter __________ it was?

12. Has it been announced __________ the planes are to take off in time or not?

11. Why and how he left the company ____________(be) still a mystery.

10. __________ he saw was quite different from __________ he was told.