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.