• Present Perfect for Unfinished Time

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• We can use the present perfect tense for unfinished actions. These are actions that started in the past and continue in the present. Use a time expression (this week, so far, until now, etc.) with present perfect and unfinished time.

  
  

  Present Perfect

  - She has studied in the library all year.

  (She studied in the library in the past and will continue to study there.)

  Past Simple

  -She studied in the library all year.

  (She studied in the library this year and the year is over.)
•  Click on the play button to hear the audio

• Statements	The professor has reviewed many projects this week. Today has been a very busy day.
  Negative	He hasn't thought about changing his major until now.
  Question	How many books have you read so far?

Source : Alison