Cau 9

1, B - series

2, D - between

3, B - protecting

4, A - during

5, C - built

6, B - remains

7, D - which

8, A - stretches

9, C - guarded

10, B - died

Cau 10

1, He didn't go to school because he had to stay at home to look after his sick mother.

2, Your friend does your work and the assignmets.

3, What did her father give her as a present at her birthday?

4, They are going to Ha Noi to celebrate the festival with their friends next week.

5, There are more people out of work in this country than ever before.

Cau 11

1, I had my bike repaired by my brother yesterday.

2, I has an intention of coming over to pick you up.

3, The thick fog made it impossible for me to drive to work.

4, She is wearing sunglasses so that the sun can't hurt her eyes.

5, They have been to Nha Trang for two years.