Choose the correct answer

9. The boy looks very proud ___ his success at school.

A. on

B. of

C. at

D. in

10. When the trucks leave the police, the ground is covered ___ trash.

A. in

B. by

C. with

D. of

11. You have read this article on the website,________?

A. don't you

B. aren't you

C. didn't you

D. haven't you

12. All the students are looking forward ___ their summer vacation in the countryside.