2.  more polite
 more formal
 Direct question:
What time does the train leave?
 Embedded question:
Could you tell me what time the train leaves?

3. Introduction + question
 use an introductory phrase
 use a question word
(what/where/who/why/which/when)
 change the word order in the question
Could you tell me what time the train leaves?

4. Introduction + question
Do you have any idea if the bus is on time?
 use an introductory phrase
 use if/whether
 change the word order in the question

5.  Do you know … ?
 Can/could you tell me … ?
 Could you let me know … ?
 Do you have any idea … ?
 I would be (most) grateful …
 Please let me know …
 Do you happen to know … ?
 I wonder / was wondering …
 Would you mind telling me … ?
 Can / May I ask … ?
 I’d like to know …