The key answer of exercise 1

a)

1. first
2. second
3. third
4. fifth
5. twelfth
6. thirteenth
7. twentieth
8. twenty-first

b)

1. third; fourth
2. sixth; eighth
3. ninth; eleventh
4. eighteenth; twenty-second
5. fifteenth; twentieth
6. twenty-first; twenty-eighth
7. twenty-third; twenty-second
8. thirtieth; thirty-first

c)

1. 25/12; the twenty-fifth of December
2. 31/10; the thirty-first of October
3. 1/1; the first of January
4. 4/7; the fourth of July
5. 14/2; the fourteenth of February