5. witness　　　　 6. possibility　　　 7. research　　 8. convincing

1-5 BD DCD　 6-10 AC CDC　 11-12DC

1. frightening　　　 2. nightmare　　　 3. puzzles　　　 4. favourite

5.Where have you been? I’m waiting for you for a long time.　　　　　　 have been waiting

4.So far,we built more than 15 bridges over the Yangts River.　　　 have built

3.A large number of students has spoken at the meeting.　　　　　　　　　　 have

2.My father has been worked in that company for 20 years.　　　　 working

1.It was six years since they graduated from that middle school.　　 is

7.Both of them have a similar hobby,which is to collect information about Yetis.

6.Liu Xiang ran very fast and won the first with an amazing speed.

5.If I don’t see it with my own eyes,I won’t believe there exists a Yeti.