I.
1. I have bought a laptop but I have not used it
2. I have written a blog but I have not uploaded any photos to it
3. We have started the game half an hour ago but we have not finished it
4. My dad has been London but he hasn't seen Big Ben
5. I have read my English book but I have not done my English homework
II.
1. Have you finished your homework yet?
2. Under this printer is guarantee
3. We haven't had a vacation since last year
4. They alway give warm clothes to homeless people in Ha Noi
5. Volunteering makes a difference in our community