Present Perfect or Past Simple (2)?

Use the Present Perfect + how long?, for, and since to talk about a period of time from the past until now.
How long have you been married? I've been married for 10 years. (= I'm married now)

Use the Past Simple + how long? and for to talk about a finished period of time in the past.
How long was the married? He was married for two years. (=He's not married now)

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Don't use since with the Past Simple. He was Prime Minister since 1998.
You have to use from... to. He was Prime Minister from 1999 to 2003.