• Present Perfect

• Read and listen. Listen again and repeat.
• 
• The present perfect tense shows actions in the past without a specific time. Use present perfect with have/has and a past participle.

  
  

  subject + have/has + past participle

  -My academic advisor has taught me a lot.

  -I have taken Professor Smith's class three times.
• You can also use present perfect for negative statements and questions.
• Negative statements 

  subject + have/has + not + past participle

  I have not seen the laboratory.
• Questions 

  have/has+ subject + past participle

  Has John taken his exams? Yes, he has./No, he hasn't.

• Emily has joined a study group.  They have walked on campus before.  Have you met your academic advisor?

  Emily has not looked at her notes. We have not seen the quad.  Yes, I have.  He's very helpful!

Source : Alison