题目：
用所给词的适当形式填空。
1. At that moment I saw a dog _______(lie) on the floor.
2. At the beginning of the _______(twenty) century,the world's population was 1.7 billion.
3. The _______(shelf) in his study are full of science books.
4. Of all the lessons in Book Three, Lesson Five is the _______(little) interesting.
5. The dog's _______(die) made her very sad.
6. There _______(be) many changes over the years.
7. Who teaches _______(they) physics?
8. How _______(excited) it is to go roller skating here.
9. Most of the students work hard _______(get) high marks in exams.
10. We can live _______(comfortable) in Taizhou because it's a good place.
答案：
1. lying 2. twentieth 3. shelves 4. least 5. death
6. have been 7. them 8. exciting 9. to get 10. comfortably
