Mars is the fourth planet from the sun and is commonly known as the Red Planets. The rocks, soil and sky
of it are a little red or pink. Its name was given by the Romans in honor of their god of war.
        People on the earth need oxygen to breathe. There is almost no oxygen on Mars. Living on Mars would be
like living on a very high mountain. There would be little air. It might be 50 degrees above zero at noon and 100
degrees below zero at night. We know that Mars has carbon. Through a telescope, Mars looks red. In some
places, it seems gray. At times the gray turns gray-green, then brown, then gray again. The gray-green may be
a kind of plant color which changes with the seasons.
        Life is expected on Mars by scientists, because there are distinct seasons on the planet's surface. This
condition might support plants. However, some researches find if Mars had life, it must have been a long time
ago. For Mars' first 600 millions years, it had plenty of water and proper temperatures for life. But now the
planet's environment has changed. Mars is not a pleasant place for any form of life.
1. 根据解释，在短文中找出相应的单词或短语。
    ______: famous        ______: sometimes
2. Its name was given by the Romans in honor of their god of war.
(改为主动语态的句子) __________________________________________________________________
3. Why is life expected on Mars by scientists?
(回答问题) __________________________________________________________________
4. There is almost no oxygen on Mars.
(改为反意疑问句) There is almost no oxygen on Mars, _____ _____?
5. But now the planet's environment has changed. Mars is not a pleasant place for any form of life.
(翻译成汉语) __________________________________________________________________