=127.(10+90)

=127.100

=12700

I. Choose the best answer from A, B, C or D to complete these sentences.

1. At the weekend we can play 'a. . ......... of badminton or join in a football match.

A. sport B. game C: Sports game D. match game

2 Kien is not very. . . . -. . . He never plays games

A. sport B. sporty C. sporting D, unsporty

3. My brother likes watching TV. . . . . I like going out with my friends

A, and B, but C. or D. so

4. I want to work in television industry,. . . . . . . . . I am working hard

A because B. although, - C. so D. and

5. Bangkok is. . . . . . capital of Thailand:

A. a B. one C. X D. the

6. There are. ...................... . girls in his class.

A not B no C. none D. any

7. . . . . . . . She plays the piano!

A How beautiful B. How Beautifully C. What good D. What well

8. On. . . we often go out.

A. nights of Saturday B. Saturday nights C. Saturday’s nights D. none is correct

9. I don 't want much sugar in coffee, Just. . . , please.

A little B. a little C. few D. a few

10. "TV just received a scholarship" - .....................".

A . Really B. Thank you C. Congratulations D, Well

11. They canceled their picnic,. . . . . the bad weather.

A because B. because of C. when D. and

12 ................ the program is late, we will wait to watch.

A When B. Because C, Although D. So

13. You can watch Harry Potter on TV. . . . . . . ... . . . You can read it

A. so B. When C. But D. or

14 “.............................................”

A. He is of medium height, with black hair and dark skin.

B. What does your new friend look like? A. What is your new friend like?

C. How is your new friends.

D. What does your new friend like ?

15............. Do you play table - tennis? "- Every weekend.

A. When B. How often C. how D. What time

16. - "Excuse me. I am looking for a telephone box ”- There is one. . . .

A straight B. straight ahead C. turn right D. going left

17. “Would you like me to turn off your computer? ”

- . . . . . . . . . . . . . . . I 'll do it myself.

A. No thanks. B Yes, please C. Don't do it D. Of course

18. My parents always say that I. . . . . . take thing without asking.

A needn 't B. mayne C. Shouldn 't D. won 't

19. Vietnam celebrates Tet, but Korea. . . .

A does B. doesn 't C. celebrate D. celebrates

20. It 's cold. The students. . . . . . . . . . . . . . . warm clothes.

A vear B. wears C. wearing D. are wearing

201 là đúng đấy mình thử rồi

Ta có : n3−nn3−n = n(n2−1)n(n2−1) = (n−1).n.(n+1)(n−1).n.(n+1) Vì (n−1).n.(n+1)(n−1).n.(n+1) là tích 3 số nguyên liên tiếp nên sẽ có 1 số chia hết cho 2 và 1 số chia hết cho 3, vậy tích trên chia hết cho 6 Do đó : n3−nn3−n chia hết cho 6 với mọi số nguyên n.