• Present Perfect/Past Simple

• Read and listen. Listen again and repeat.
• 
• Use the past simple tense for actions/events that happened at a specific time in the past and for finished actions.
  

  
  

  Use the present perfect tense to show actions in the past without a specific time and unfinished actions.
•  Click on the play button to hear the audio

• Present Perfect	Past Simple
  She has enjoyed her psychology classes. (Non-specific time)	She enjoyed her psychology classes last semester. (Specific time)
  I have gone to the science lab twice. (Non-specific time)	I went to the science lab twice yesterday. (Specific time)
  My senior year has been really difficult. (Unfinished action)	My senior year was really difficult. (Finished action)

Source : Alison