1 are -> is 

-> leisure activities ko đếm đc nên đi với is 

2 staying -> to stay 

-> decided + to V 

3 too many -> too much

-> much đi với dt ko đếm đc

4 relaxed -> relaxing 

-> vật + adj + v-ing 

5 sound -> sounds 

6 in front -> in front of : đằng trước 

7 on -> from 

8 carfully -> carefull 

-> ta có cụm từ be carefull : cẩn thận 

9 to have -> having 

-> destest + v-ing 

10 to come -> coming 

-> fancy + v-ing 

11 to open 

-> do you mind + v-ing 

12 to learning -> learning

13 ở đây thiếu V rùi mà ta chỉ có 1 V đi với comics : read comics  -> reading comics 

-> prefer + v-ing 

14 to make -> making 

-> enjoys + v-ing 

15 are -> is

1.Having leisure activities are truly important to the elderly.->is-have leisure activities+is
2.Although she wanted to go to the museum , she decided staying at home.->to stay-decide+toV
3.Parents are concerned that their kids may be spending too many time on screens.->spent
4.Collecting coins is exciting , but it can also be relaxed.->relaxing-tobe+adj
5.Clod watching sound weird, but Hang adores it.->sounds
6.For some young people ,enjoyment involves sitting in front a computer playing games.->in front of
7.His parents are thinking of banning him on using the computer.->from-ban sb from
8.When you game online, be carefully when making friends with strangers.->careful-be careful:hãy cẩn thận

9. I detest to have to get up when it’s dark outside.->having-detest+Ving

10. Do you fancy to come on a day trip to Bath next Saturday?->coming-fancy+ving

11. Would you mind to open the window? ->opening-would you mind+Ving

12. Why are they encouraged to learning English?->to learn-encourage+toV

13. I preferred comics in my free time.->reading comics

14. Mai enjoys to make crafts, especially cloth dolls.->making-enjoy+Ving

15. For some people, training pets are hard work.->is-training pets+is