The correct sentence is 'How long have you been married' . This is the present perfect tense and we use it to describe an action or state that started in the past and continues to the present moment. be married = be united in marriage with someone. (this can continue for years) get married = become married this refers to when someone started married life/ the action of becoming married in a marriage ceremony 'They have just got married' (this happens once it is not a state that continues) To marry ( past / past participle = married) refers to the action of becoming/ getting married. (This happens once and is not an action that continues) 'How long' can only be used to ask about states or actions that continue or continued over a period of time. 'How long did you live in London for?' 'How long have you lived in London?'

The second one.

For "how long" you are asking about the length of certain period. Thus 1 and 3 are simply wrong because both of them are one single action that happens at some point, not lasting.

2）How long have you been married?

第二个，因为marry 是瞬间动词。