why don't we eat in the canteen 
=> shall......
let's clean the classroom
=> I think....
shall we paint the school gate 
=> I suggest that ....
lẹ mn ơi

Why don't we eat in the canteen?

⇒Shall we eat there together?

-----------------------------------

Let's clean the classroom.

⇒I think it would make the room much nicer.

-----------------------------------

Shall we paint the school gate?

⇒I suggest that we choose a bright color to make it look more welcoming.

-----------------------------------

Công thức :

Why don't we + VP?

Shall we + VP?

Let's + VP.

I think +S + should + VP.

Shall we + VP?

I suggest that + S + VP.

`1. ` Shall we eat in the canteen`?`

`-` Will/Shall + S + V-inf ?
`2. ` I think we should clean the classroom.

`-` I think + Clause

`-` I think + S + should + V

`=>`  Đưa ra một lời khuyên dành cho một ai đó nên làm việc nào đó.
`3. ` I suggest that we paint the school gate.

`-` S1 + suggest +(that) +  S2 + (should) V + O.