[has/have + past participle]
The Present Perfect is used to express:
1. an action which started in the past and continues up to the present.
• They have been married for twenty years.
• How long have you known each other?
2. an action which happened at an unstated time in the past.
The Present Perfect is used with the following time expressions:
• just, lately, never, ever, yet, since, for, already