1. How many boxes has Mary carried upstairs?

=> câu đã cho có one box -> câu hỏi có how -> how many: có bao nhiêu

2. When did your mother teach you how to cook?

=> có mệnh đề when I was a little girl, câu hỏi có When

3. Whose son did I have lunch in the canteen with?

=> có Mr. Thomas's son

4. How much vinegar should I use for dipping sauce?

=> có little

5. How often does my father come home for lunch?

=> có once a week -> chỉ tần suất