14. I ......have read..... (read) this book several times

15. He .....has stopped....... (stop) drinking since his father's death

16. He .....hasn't been.... (not/be) there yet

17. I ..'ve learnt....... (learn) how to be have since I was born

18. Up to now, we ....'ve made...... (make) three sentences

19. have You .....eaten....... (eat) this kind of food ?

20. We .....have been..... (be) here since the president ......appeared........ (appear)