21. ______ the course very difficult, she decided to move to a lower level.

20. Please send us all the information ______ you have about the candidate for the position.

30. Scientists have obtained more evidence ______ plastic is finding its way into the human body.

Part Ⅴ Applied Writing (20 Points)Directions: This part is to test your ability to do practical writing. You are required to write a Certificate of Employment according to the information given in Chinese below. You should write your letter (no less than 100 words) on the Answer Sheet.假如你是李明，你的学生李伟华想在你的美国朋友约翰逊教授的大学申请一个职位，请写一封推荐信以帮助他成功通过申请。

18. —John, What ______ in your hand?—Look! It‘s a birthday gift for my grandma.

（ ）53.Dan is interested in taking wildlife photographs and enjoys the kind of programme which gives him a chance to see a professional photographer at work.

63.我们真希望你昨晚没那么多工作要做,因为我们都知道你肯定会在晚会.上玩得很开心。

36. Dr. Aiken cut the background from the photos for the purpose of______.

22. Not until the motorbike looked almost new ______ repairing and cleaning it.

31. Many businesses started up by college students have ______ thanks to the comfortable climate for business creation.

（ ）51.Although Rob lead a quiet life in a small village, that doesn’t stop him from wanting to find out about the latest scientific development.

24. Only after my friend came ______.