• It is snowing. = Is it snowing?
• He can speak German. = Can he speak German?
• They have lived here a long time. = Have they lived here a long time?
• She will arrive at ten o'clock. = Will she arrive at ten o'clock?
• He was driving fast. = Was he driving fast?
• You have been smoking. = Have you been smoking?

If there is no auxiliary, use Auxiliary 'do'.

• You speak fluent French. = Do you speak fluent French?
• She lives in Brussels. = Does she live in Brussels?
• They lived in Manchester. = Did they live in Manchester?
• He had an accident. = Did he have an accident?

Most questions with question words are made in the same way:

• How often does she use it?
• Why don't you come?
• Where do you work?
• How many did you buy?
• What time did you go?
• Which one do you like?
• Whose car were you driving?

Note "who", "what" and "which" can be the subject.
Compare:

• Who is coming to lunch? (who is the subject of the verb)
• Who do you want to invite to lunch? (you is the subject of the verb)
• What happened? (what is the subject of the verb)
• What did you do? (you is the subject of the verb)

Note the position of the prepositions in these questions:

• Who did you speak to?
• What are you looking at?
• Where does he come from?

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• Where is Johnny?
• Has he found it yet?

If there is no auxiliary, use Auxiliary 'do, does or did '. For example:

• What time did he arrive?
• How often do you play tennis?

Indirect  Questions

However, when we ask for information,
we often say  'Do you know…?' or 'Could you tell me….?'

These are indirect questions and more polite.

Note that the word order is different. For example:

• Do you know where Johnny is?
• Have you any idea if he has found it?

Note that we don’t use do, does or did. For example:

• Could you tell me what time he arrived?
• Would you mind telling me how often you play tennis?

Use if or whether when there is no question word.

• Has he done it? = Do you know if he has done it?
• Is it ready? = Can you tell me if it is ready?

The same changes in word order happen
when we report questions.

Note that in reported questions,
the verb changes to the past:

• What are you doing? = He asked me what I was doing.
• What have you done about it? = He asked me what I had done about it.
• Do you work with Pamela? = He asked me if I worked with Pamela.