of people use cell phones => Cell phones
2. Nga does her homework every day.=> Her homework.
3. Mrs Mai taught students 6c English.=> Students 6c.
4. He gave her some flowers yesterday .=>
5.They have finished their homework.=> Their homework.
6.He has lost his keys for 2 days .=> His keys
7.. They have done their homework.=> Theitr homework....
8.Do you clean the house evey day?.>........the house.
9. Did you buy this dictionary two weeks ago?=>...........this dictionary....
10.Noone helped him with homework .=> He
11. Nam doesn't clean the house everyday .=> The house..
12. He didn't do housewrk yesterday
=> Housework....