Present Perfect

1. Talk about things that started in the past, continue up to the present and may continue into the future

2. Use

2.1. Actions

2.1.1. which happened at unspecified (unknown) time in the past

2.1.2. in the past which have an effect in the present moment

2.1.3. which began in the past and continue in the present

2.1.3.1. + for + a leght of time

2.1.3.2. + since + a point in the time

2.1.4. which began in the past and it is finished

2.1.4.1. She's read the book ( She's finished the book)

2.1.5. Talk about things that have happened in a time period that is not finished, such as today, this month, this years

2.1.5.1. I've had 2 cups of coffee today

3. Form

3.1. Subject + have/has + past participle

3.1.1. I have bought new shades

3.2. Subject + haven´t/hasn´t + past participle

3.2.1. He hasn't taken any drug for two years

3.3. Have/has + subject + past participle

3.3.1. Where has she lived for the past 21 years?