21. Thanks to _____invention of the telephone, people can chat with ________ others in different places.

   A. the; the                     B. /; the                    C. /;/                            D. the;/

22. --Tom works hard at English?
   -- _____, and _____.
   A. So does he; so you do      B. So you do; so is he
   C. So he will; so do you        D. So he does; so do you