6. B
7. D
8. C
9. A
10. A
11. A
12. A
13. A
14. B
15. C
16. B
17. C
18. A
19. C
 

b: 

=>x(y-3)+3(y-3)=17

=>(y-3)(x+3)=17

\(\Leftrightarrow\left(x+3,y-3\right)\in\left\{\left(1;17\right);\left(17;1\right);\left(-1;-17\right);\left(-17;-1\right)\right\}\)

hay \(\left(x,y\right)\in\left\{\left(-2;20\right);\left(14;4\right);\left(-4;-14\right);\left(-20;2\right)\right\}\)

a: =>x(2y+3)+2(2y+3)=5

=>(2y+3)(x+2)=5

\(\Leftrightarrow\left(2y+3;x+2\right)\in\left\{\left(1;5\right);\left(-1;-5\right);\left(5;1\right);\left(-5;-1\right)\right\}\)

hay \(\left(y,x\right)\in\left\{\left(-1;3\right);\left(-2;-7\right);\left(1;-1\right);\left(-4;-3\right)\right\}\)

1. played

2. Did - go

3. didn't study

4. has

5. has

6. Does - live

7. are meeting

8. are visiting

9. isn't reading

10. didn't go

11. didn't watch - did

12. met

13. rained

14. fly

15. fries

16. closes

17. didn't go

18. taught

19. did - do

20. met

21. didn't go

22. isn't painting

23. aren't planting

24. Are - making

25. is repairing

26. 

=>x(y-3)+3(y-3)=17

=>(y-3)(x+3)=17

\(\Leftrightarrow\left(x+3,y-3\right)\in\left\{\left(1;17\right);\left(17;1\right);\left(-1;-17\right);\left(-17;-1\right)\right\}\)

hay \(\left(x,y\right)\in\left\{\left(-2;20\right);\left(14;4\right);\left(-4;-14\right);\left(-20;2\right)\right\}\)

7C

8D

9A

10C

7-C.

8-C.

9-A.

10-C.

7-C        8-C           9-A        10-A

31 whom

non-defining

32 whom

defining

33 who

defining

34 whom

defining

35 who

non-defining

36 which

non-defining

37 which

defining

38 who

defining

39 which

defining

40 which

non-defining

mik gửi cho  bạn 4 mẫu rui đấy

11 She asked me if I like English music

12 Two department stores have been built

13 The computer is being used at the moment

31 We should avoid playing computer games because it will hurt our eyes

32 Rescue workers sent water and food to victims yesterday

33 I like to travel to Europe but I don't have enough money

34 Our children will be taken care of by robots in 20 years' time