Read the passage and answer the questions. Can humans migrate to Mars? As early as more than a century ago, in science fiction, human beings began to

2.① The diameter of Mars is about half that of the earth; ② 1/3 gravity; ③ The atmospheric concentration is equivalent to1100 on the earth; There is water on Mars.

3. Zublin: Is there life outside the earth? Friedman: Understanding the origin and destination of life.

At a place, "we will have to examine the relationship between human beings and the earth" is the foundation, because we can't immigrate to Mars, and the earth is our only home. Further emphasize the importance of protecting the earth.

5. "Omission"