10. Unless you study harder, you will fail the next exam.
11. Unless he practices writing every day, he can't improve his writing skill.
12. Unless you return this book to the library today, you'll have to pay a fine.
13. Unless I knew the number, i would not ring her up.
14. Unless Peter studied hard, he couldn't get good marks.
15. It was not until 1915 that cinema became an industry.
16. It was not until my son was 5 that he started talking.
17. It was not until Lan was 35 that she went abroad
18. It was not until midnight that we went to bed.
19. He gave me his address in order to visit him
20. He studies hard in order not to fail the exam
21. She turned down the radio in order not to disturb the neighbors.
