15/ Look ! The sun is setting behind the moutains
2/ Mary felt asleep while she was reading magazine last night. 
14/ last week , thay decide paddle xuan huong lake by renting a canoe
8/ he is old enough to go to school
7/ her teacher asked him  spent more time do home work 
11/ i haven't seen mai since we left school

6. Bao always forgets to do his homework. 
7. The teacher asked him to spend more time doing homework. 
8. he is old enough to go to school. 
9. Last night, she was listening to music at 10.30 o'clork. 
10. These exercises are too difficult for the students to do without mistakes. 
11. I haven't seen Mai since we left school. 
12. I am happy to pass all the exams. 
13. A girl was riding when an accident happened. 
14. Last week, we decided to paddle to Xuan Huong lake by renting a canoe. 
15. Look! The sun is setting behind the mountains.