You might have heard that Dustin was dismissed.

1. Have you ever been to Britain?

2. I have been to London twice.

3. Tim has discussed his paper with his supervisor/faculty advisor(美).

4. He has been watching TV for two hours.

5. Have you sent postcard to your uncle?

6. I told Maggie to send it for me.

7. Haven't I told you the address to the letter might be wrong?

8. I should have checked it.

9. You might have heard that Dustin was dismissed.

10. You must have got the news that postage is going to be raised.

11. Peter had thought a lot about quitting before he did it.

12. He had become an Olympic champion by the age of twenty.

13. Beijing successfully won the bid for the 2008 Olympic Games.

14. It has tried eight years before, but failure.

15. Having successfully concluded their project, Melissa is spending her holiday in Singapore.