1.Hoa and Lan bought some books yesterday 

Hoa and Lan didn't buy some books yesterday 

Did Hoa and Lan buy some books yesterday ?

2.Our friends are watching a game on TV at the moment

Our friends aren't watching a game on TV at the moment

Are your friends watching a game on TV at the moment ?

3.Ba's teacher gave him a lot of homework last week

Ba's teacher didn't give him a lot of homework last week

Did Ba's teacher give him a lot of homework last week ?

4.our class will go to the zoo next week

our class won't go to the zoo next week

will your class go to the zoo next week ?

5.their grandmother told them a lot of stories last year

their grandmother didn't tell them a lot of stories last year

did their grandmother tell them a lot of stories last year ?

6.Look ! Lan is wearing a new dress

Look ! Lan isn't wearing a new dress

Is Lan  wearing a new dress ?

7.They enjoy watching TV

They don't enjoy watching TV

do they enjoy watching TV

8.Hoa's mother went shopping yesterday

Hoa's mother didn't go shopping yesterday

Did Hoa's mothergo shopping yesterday?

9.we are visiting our grandparents this weekend 

we aren't visiting our grandparents this weekend 

are you  visiting your grandparents this weekend ?

10.received 

I didn't receive a letter yesterday

 did you receive a letter yesterday ?

11.are singing

Listen ! The birds aren't singing beautifully

are the birds singing beautifully ?

12.live

we don't live in a big city

do you live in a big city ?

13.has

she doesn't have breafast at 7 a.m every morning

does she  have breafast at 7 a.m every morning ?

14.learn

they don't learn something about geography 

do they learn something about geography ?

15.helps

Lan doesn't help her mother with the homeworks

does lan help her mother with the homeworks ?

Good luck ^^