There are three main types of questions. Each of these question types can be used to form polite questions. Here's a quick overview of the three types of questions in English:
Where do you work?
Are they coming to the party?
How long has she worked for this company?
Can you tell me where he plays tennis?
I wonder if you know what time it is.
Do you think she will be able to come next week?
You live in New York, don't you?
She hasn't studied French, has she?
We're good friends, aren't we?
Direct and indirect questions are used to ask about information you do not know. Question tags are generally used to check information you think you know.
Making Direct Questions Polite
Direct questions can seem impolite at times, especially when you are asking a stranger. For example, if you come up to someone and ask:
Does the tram stop here?
What time is it?
Can you move?
It is certainly correct to ask questions in this manner, but it's very common to make these types of questions more polite by adding 'excuse me' or 'pardon me' to begin your question.
Excuse me, when does the bus leave?
Excuse me, what time is it?
Pardon me, which form do I need?
Questions with 'can' are made more polite by using 'could':
Excuse me, could you help me pick this up?
Pardon me, could you help me?
Pardon me, could you give me a hand?
Another way of making direct questions more polite is to add 'please' at the end of the question:
Could you fill in this form, please?
Could you help me, please?
Can I have more soup, please?
Please, can I have more soup?
Indirect Questions: Very Polite
Using indirect question forms is an especially polite way of asking polite questions. The information requested is the same as in direct questions, but are considered more formal. Notice that an indirect question begins with a phrase (I wonder, Do you think, Would you mind, etc.) the actual question is then placed in positive sentence form:
Introductory phrase + question word (or if) + positive sentence
I wonder if you could help me with this problem.
Do you know when the next train leaves?
Would you mind if I opened the window?
NOTE: If you are asking a 'yes - no' question use 'if' to connect the introductory phrase with the actual question statement. Otherwise, use a question word 'where, when, why, or how' to connect the two phrases.
Do you know if she will come to the party?
I wonder if you can answer a few questions.
Can you tell me if he is married?