Here are the underlined correct words:
11. They **make** wreaths at this time of year.
12. Dad **makes** a special dish on his birthday.
13. Please **do** the dusting today.
14. She is **doing** the washing-up.
15. Mum is **doing** the shopping.
**Explanation:**
This part focuses on the usage of 'do' and 'make'. Generally, 'make' is used when you are creating or constructing something, like a dish or a wreath. 'Do' is used for activities or tasks, like the dusting or washing-up. The choice depends on whether the action results in the creation of something or is a general activity.