Use THE PRESENT PERFECT TENSE or THE PRESENT PERFECT CONTINUOUS to fill in the blanks:
1. I’m tired. We …. (walk) for over an hour. Let’s stop and rest for a while.
2. The zoo isn’t far from here. I … (walk) there many times.
3. I …. (write) my friends at least a dozen letters since I left home and come home.
4. Sally is writing a letter to her boyfriend. She …. (write) it since she got home from class. It’s going to be a long letter.
5. The telephone ….. (ring) four times in the last hour, and each time it has been for my roommate.
6. The telephone … (ring) for almost a minute. Why doesn’t someone answer it?
7. She is 80 and she … (never / read) a book in her life.
8. The secretary is very tired. She … (type) all morning.
9. Tom is reading a book. He started two hours ago and he is on page 53. He .. (read) for two hours.
10. Hello! I … (clean) the windows. So far I … (clean) five of them and there are two more to do.
11. My grandfather … (died) 30 years ago. I …. (never / meet) him.
12. A: Is your father at home?
      B: No, I’m afraid he … (go) out.
      A: When exactly … (he / go) out?
      B: About ten minutes ago.