1．地球的体积是月球的49倍。 The earth is _____ ______ ______ _____ of the moon.

10. Plants supply o_________ to animals to breathe.

9．An astronomer observes the space through t_______.

8. They stood still, looking at the balloons_________ (漂浮) in the air.

7. His health _______(逐渐地) improved.

6. _________ (全球的) warming has become a big problem.

5. The dogs can be trained to detect the _________ (存在) of explosives.

4. With the _________(发展) of modern society, many new techniques have been developed.

3. Many kinds of _________ (方法) of payment have been used in daily life.

2. You can see fishes swimming on the ________ (水面) of the river because it is too warm.