Here are the plural forms:
1. Five (sheep) - five sheep
2. Seven (man) - seven men
3. Twenty (tooth) - twenty teeth
4. Eight (child) - eight children
5. Thirteen (mouse) - thirteen mice
**Explanation**:
This section requires us to use the plural form of nouns.
- 'Sheep' is a special case, its plural form is 'sheep' also.
- 'Man' becomes 'men'.
- 'Tooth' becomes 'teeth'.
- 'Child' becomes 'children'.
- 'Mouse' becomes 'mice'.