1. goodbye

2. friend

3. boy

4. how

5. ruler

6. mean

7. what

8. eight

9. seven

10. your

`II`

1. Is that Mai?

2. How old is Linda?

3. She is eight years old

4. I am nine years old

5. Are they your friend?

`III`

1. are → is

- my name là số ít (có thể coi là thế) :]]

2. friends → friend

- "this is" là chỉ số ít

3. friend → friends

- Are - Tony and Peter chỉ số nhiều

4. play → playing

- play + V_ing

5. are → is

- She là số ít

`IV`

1 - C

2 - E

3 - A

4 - B

5 - D

`V`

1. No, I don't

2. Yes, they are

  I.

1. Goodbye

2. Friend

3. Boy

4. Who

5. Ruler

6. Mean

7. What

8. Eight

9. Seven

10. Your

  II. 

1. Is that Mai?

2. How old is Linda?

3. She is eight years old.

4. I am nine years old. 

5. Are they your friends? 

  III. 

1. Are → is

2. Friends → friend

3. Friend → friends

4. Playing

5. Are → is

  IV.

1. C

2. E

3. A

4. B

5. D 

  V. 

1. No, I don't.

2. Yes, they are.