1. Which street food do you like most among (the) four street food(s)?

- I like fruit sticks the most because they are delicious and nutritious.

(Do we have to use the definite article? Do we have to use 'food' or 'foods' here?)

2. We have talked about street food in the four cities. Would you like to name the cities?
- Yes. They are New York, Ottawa, Brussels, and Beijing.

3. How much is a pretzel?
4. What is the price of a beaver tail?
5. How much does a Brussels waffle cost?
6. How much do I owe you for a fruit stick?
- It's two dollars.
(Are the questions and answers proper?)

1. If you leave "the" out, the implication is that there are only four types, no matter where you go. If you include "the," your reference seems to be the four types right near you (but maybe there are others in other places). This is simply how I take it. Other tutors may have different ideas.

2, 3, 4, and 6 are fine, yes.

5 makes me wonder if there is such a thing as a "Brussels waffle" or if you mean a waffle in Brussels. ???

1. The definite article "the" is used when referring to specific items or when something is already known or has been mentioned before. In this case, when talking about the four street foods, it is common to use the definite article "the," as you did in your sentence. The use of either "food" or "foods" depends on the context. Since you mentioned four different street foods, the plural "foods" would be more appropriate.

2. Yes, the question is proper and the answer is correct. You have correctly named the four cities which you have talked about in relation to street food - New York, Ottawa, Brussels, and Beijing.

3. The question "How much is a pretzel?" is proper. To find the price of a pretzel, you can consider multiple approaches:
- Check online: You can browse through websites of pretzel vendors or food delivery platforms to check the price.
- Visit a local bakery or snack stand: You can visit a bakery or a street vendor that sells pretzels and ask about the price directly.
- Ask someone familiar with the area: If you know someone who frequents places that sell pretzels, they might be able to give you an idea of the price.

4. The question "What is the price of a beaver tail?" is proper. Similarly to finding the price of a pretzel, you can apply the same approaches to find the price of a beaver tail. Check online or in local establishments known for selling beaver tails.

5. The question "How much does a Brussels waffle cost?" is proper. To find the price of a Brussels waffle, you can use similar methods mentioned above, such as checking online or visiting local establishments that sell waffles.

6. The question "How much do I owe you for a fruit stick?" is proper. The answer you provided, "It's two dollars," is correct. If you are purchasing a fruit stick, the person selling it will inform you of the price, which in this case is two dollars.