Помогите пожалуйста. Use less/the least/fewer/the fewest

1. Of all British cars, this one uses the least petrol. It also needs less repairs. 2. There were fewer problems than we expected. 3. Fewer girls than boys do mathematics at university. This may be because girls get less encouragement to study maths at school. 4. Of all my friends, Jane does the least work. 5. I feel less confident about the future than i did a year ago. 6. My mother is/was the least optimistic person you can imagine. 7. I've got less money than I thought. 8. As the years went by, they had fewer things to say, and less interest in talking to each other. 9. Ann's less shy than Pat. 10. I spoke English less fluently a year ago than I do today. 11. Ann was the person who made the fewest mistakes in the translation exam. 12. Do you want more time and less money, or more money and less time? 13. He drives less carefully than I expected. 14. I think this country is less prosperous than it was a year ago. 15. Liz is very clever, but she has got the least self-confidence of anyone I know. 16. It was the least successful party we'd given. 17. I've had the fewest days of work of anybody in the office. 18. People from the north of my country speak less politely than people from the south. 19. My home town is the least gorgerous place I know. 20. Less people than usual were invited to the conference but nevertheless it was a great success.