Answer:
11. so that
12. although
13. because
14. while
15. where
Explanation:
11. The guard opened the gate so that the pupils could get inside.
12. Emily still could not sleep although she was so tired.
13. Lea studies well because she wants to be a successful person someday.
14. We watched our favorite show while waiting for our dinner.
15. Jayson visited the shop where he bought his books.
