1. What time do you go to bed?
- I go to bed at 10 p.m.
2. When is your bed time?
- It is 10 p.m.
3. What is your bed time?
- It is 10 p.m.
4. What present did you receive on your birthday?
5. What did you receive on your birthday?
6. Which gift did you get on your birthday?
- I got a teddy bear.
(Are the questions and answers all correct? Would you correct some? Which one are usual expressions?)
They're all correct. 1, 2, and 5 are best -- but the others are fine.
The questions and answers you provided are correct and can all be used in conversation. However, there are some differences in their phrasing and level of formality.
1. "What time do you go to bed?" and "When is your bed time?" are both correct ways to ask about someone's regular bedtime. These questions are more formal and are usually used in a more professional or polite setting.
2. "What is your bed time?" is also correct, but it is a bit more direct and informal. It is commonly used in casual settings or when talking to friends or family.
Regarding the birthday questions and answers:
4. "What present did you receive on your birthday?" is a grammatically correct question, but it is less common in everyday conversation. A more usual expression is "What did you get for your birthday?" or simply "What did you receive for your birthday?"
5. "What did you receive on your birthday?" is a more common and natural way to ask someone what gifts they received on their birthday. It is a simple and straightforward question.
6. "Which gift did you get on your birthday?" is grammatically correct, but it is less commonly used in conversation. It is more formal and precise, and may be used when there are multiple gifts and you're asking someone to specify a particular one.
Overall, the choice of question or phrasing depends on the context, formality, and familiarity with the person you are talking to.