`21.` In free time / father / often / play / badminton / friends.

`->` In free time, my father often plays badminton with his friends.

`22.` mother / teacher / . she / teach / Maths / school / near / house.

`-> My mother is a teacher. She teaches Math at a school near our house.

`23.` brother / 17 years / and / he / grade 12

`->` My brother is 17 years old and he is in grade 12.

`24.` he / love / collect / stamps/ . He / have / hundreds / stamps/ collection.

`->` He loves collecting stamps /. He has hundreds of stamps in his collection.

`25.` please write / me soon / and tell / your / family.

`->` Please write to me soon and tell me about your family.

`26.` What time / our / class / start?

`->` What time does our class start?

`27.` How much / this mobile phone / cost?

`->`  How much does this mobile phone cost?

`28.` enjoy / listen / music because it / help / me / relax.

`->` I really enjoy listening to music because it helps me relax.

`29.`  It/ very important / protect / forests

`->` It is very important to protect the forest.

`30.` Which / longest river / Viet Nam?

`->` Which is longest river in Viet Nam ?

21 In free time , my father often plays badminton with his friends.

22 My mother is a teacher .She teaches Maths in a school near my house.

23 My brother is 17 years old .He is in grade 12.

24 He love collecting stamps.He has hundreds  collection.

25 Please write me soon and tell me about your family.

26 What time do our class start ?

27 How much does this mobile phone cost ?

28 I enjoy listening to music because it helps me to relax.

29 It is very important to protect the forest.

30 Which is longest river in Viet Nam ?