$1.$ Let's play volleyball.

- Let + O + V (Bare).

$2.$ What about going to the school cafeteria?

- What about + V-ing?

$3.$ Why don't we go to the movies?

- Why don't + S + V (Bare)?

$4.$ I am interested in playing the piano.

- interested in + V-ing.

$5.$ Don't forget to brush your teeth after meals.

- Do not + V (Bare).

- forget + to V.

$6.$ Children ought not to stay up late.

- ought + (not) + to V.

$7.$ Hoa's birthday is on next Sunday.

- S + to be + ...

$8.$ Nga would like to go to the library now.

- S + would like + to V.

$9.$ He always goes to school on time.

- S + V (s/es). 

$10.$ Liz sends a lot of stamps to Ba.

- S + V (s/es).

$11.$ How about listening to music?

- How about + V-ing?

$12.$ Why don't we play chess tonight?

- Why don't + S + V (Bare)?

$13.$ I prefer staying at home.

- prefer + V-ing.

$14.$ It's easy to collect comics.

- S + to be + adj + to V.

$15.$ It's difficult to do  Math.

- S + to be + adj + to V.

$16.$ She prefers watching TV.

- prefer + V-ing.

$17.$ What about seeing a movie with me tonight?

$18.$ They intend to buy a new bike tomorrow.

- intend + to V.

$19.$ He joins in playing marbles.

- join = take part in: than gia.

$20.$ Let's go swimming now.

1. Why don't we play volleyball?
`->` Let's play volleyball.
- Let's + V1....: Hãy làm gì
2. Let's go to the school cafeteria.
`->` What about going to the school cafeteria?
- What about + N/V_ing....?: Thế còn.... thì sao?
3. What about going to the movies?
`->` Why don't we go to the movies?
- Why don't + N + V1...?: Tại sao không?
4. I enjoy playing the piano.
`->` I am fond of playing the piano.
- fond of = enjoy/love/like + V_ing: thichs làm gì
5. Remember to brush your teeth after meals.
`->` Don't forget to brush your teeth after meals.
- Don't forget/Remember + to V1...: đừng quên làm gì.
6. Children shouldn't stay up late.
`->` Children ought not to stay up late.
- should/ought to/shouldn't/ought not to: nên làm gì/không nên làm gì
7. Next Sunday is Hoa's birthday.
`->` It'll be Hoa's birthday next Sunday.
- Thì tương lai đơn: will + V1
8. Nga wants to go to the library now.
`->` Nga would like going to the library now.
- would like + V_ing/to V1: muốn làm gì
9. He is never late for school.
`->` He always goes to school on time.
- S + always/usually/sometimes/.... + Vs/es
10. Ba receives a lot of stamps from Liz.
`->` Liz gives Ba a lot of stamps.
- receive (v): nhận/give (v): tặng
11. Why don't you listen to music?
`->` How about listening to music?
- How about + V_ing = What about + N/V_ing....?: Tại sao không?
12. Let's play chess tonight.
`->` Why don't we play chess tonight?
- Why don't + N + V1...?: Tại sao không?
13. I would rather stay at home.
`->` I prefer to stay at home.
- prefer (v): dự định = rather (adv): dự định
14. Collecting comics is easy.
`->` It's easy to collect comics.
- It's easy to + V1: Nó dễ để làm...
15. I find math difficult.
`->` It's difficult to learn math.
- It's difficult to + V1: Nó khó để làm...
16. She likes watching TV better.
`->` She prefers watching TV.
- like = prefer + V_ing/ to V1: thích làm gì
17. Would you like to see a movie with me tonight?
`->` What about seeing a movie with me tonight?
- What about + N/V_ing....?: Thế còn.... thì sao?
18. They are going to buy a new bike tomorrow.
`->` They intend to go/going to buy a new bike tomorrow.
- intend = going to: dự định làm gì
19. He takes part in playing marbles.
`->` He joins in playing marbles.
- join in = take part in: tham gia
20. Should we go swimming now?
`->` Let's go swimming now.
- Let's + V1....: Hãy làm gì