1. three hundred"and"twenty-one

2. one half / one-half / a half

3. four fifths / four-fifths

4. three forty-five / fifteen (minutes) to four / a quarter to four

5. five twenty-five / twenty-five (minutes) past five

6. nineteen hundred"and"five / nineteen o five

7. ninety-six point zero five

8. twenty-three percent

9. May 10th / May the tenth

10. No. 8

11. in the 1930s / in the nineteen thirties

12. the twenty-first lesson / Lesson 21 / Lesson Twenty-one

【解析】参考教材 第四章 数词  3.数词的应用