a.S=1-2+3-4+...+99-100

  =(1-2)+(3-4)+...+(99-100)

  =(-1)+(-1)+...+(-1)

Vì từ 1->100 nên có 50 cặp 

=> có 50 số -1

=>(-1)+(-1)+...+(-1)=-50

=>1-2+3-4+...+99-100=-50 

b. n + 5 chia hết cho n - 2

n - 2 + 7 chia hết cho n - 2

Mà n - 2 chia hết cho n - 2

=> 7 chia hết cho n - 2

n - 2 thuộc Ư(7) = {-7 ; -1 ; 1 ; 7}

n - 2 = -7 => n = -5

n - 2 =-1 => N = 1

n - 2 = 1 => n = 3

n - 2 = 7 => n = 9

Vậy n thuộc {-5 ; 1 ; 3 ; 9}

Toán nha lộn

we are going to see a movie at a 3D cinema 
 (to see ko hợp lý cho lắm)

We are going to see a 3D movie at the cinema

dịch ra là tôi có một anh trai và một chị gái

=> i have three siblings

It's a good idea for us to do exercises every morning.

1. We were climbing in the mountain when it started to rain

2. Jack was talking to his friends when the ball hit his head.

3. While the boys were playing soccer, the girls were dancing.

1. Lỗi sai: isn't --> are not

2.Lỗi sai: little --> few

3. Lỗi sai: any --> some

4.Lỗi sai: any--> some; some--> any

5. Lỗi sai: few --> little

6. Lỗi sai: many --> some

7. Lỗi sai: any --> some

8. much --> many

9. Lỗi sai: some --> any

10.a lot of --> any

11.what --> where

12. a lot of --> any

13. kid --> kind

14. yoru --> your/ when --> how often

15. homework --> his homework

16. near to --> near

17. very --> any

What's your name?

what is your name?

1. Tam used to type fast. (used to V: đã quen làm gì trong quá khứ nhưng giờ thì không còn nữa)

2. I'm very sad not to be accepted in that group. (tính từ + to V)

3. Is this the first time you have played a computer game? 

S + have/has + never + V(P2) +....+ before. = It is the first time S +  have/has + V(p2). 

Mai enjoy making crafts, especially bracelets.

Kết quả: making

1. Lan doesn't like rock music, Huong doesn't,either

3. English is  more interesting than Maths.

4. The red car is not cheaper than the black one.

5. They stayed at home last night, so did their children.

Chào em, em tham khảo nhé:

2. Lan doesn't like rock music, and neither does Huong. (either)

=> Lan doesn't like rock music, and Huong doesn't either.

3.Maths isn't as interesting as English.

=> English is more interesting than Maths.

4. The black car is cheaper than the red one.

=> The red car is not as cheap as the black one.

5. They stayed at home last night, and their children did too (so)

=> They stayed at home last night, and so did their children.

Chúc em học tốt.