二、短文填空。
阅读下面短文，在空白处填入一个适当的单词或用括号内单词的正确形式填空。
The sun is important to the earth. It
9. ______ (give) the earth heat and light. So
humans and other 10. ______ (live) things
can live on the earth. But there 11. ______
(be) one big problem that humans have to
think about: Will the sun disappear one day?
12. ______ will the sun die? It won't be
any time soon. It will be in 5 billion 13. ______
(year).
Scientists from the University of
Manchester in the UK predict (预测) that in
about 5 billion years 14. ______ now, the
sun will turn into a "Red Giant (红巨星)".
This is the name that scientists give to a star at
the end of 15. ______ (it) life.
When our sun becomes a red giant, its
center will shrink (萎缩). 16. ______ the
outer layer (外层) will expand as far as Mars.
Scientists say no humans will 17. ______
(survive) on the earth when the sun dies out.
The sun is still 18. ______ (youth)
now. It is just 4.6 billion years old. This means
it is just more than one third into its lifetime.

三、书面表达。
通过本单元的学习，同学们对神秘的太空充满了兴趣。在英语口语课上，同学们对“探索太空是否值得”这一话题展开了分组讨论。请你根据下面表格中的信息，以“Is Space Exploration Worthwhile?”为题用英语写一篇短文，向全班汇报你们小组的讨论结果。
Is Space Exploration Worthwhile?

参考词汇：worthwhile（值得的）；be worth doing sth.（值得做某事）；weather forecast（天气预报）
写作要求：
1. 文中须包含表格中的所有信息，可适当发挥；
2. 文中不得出现本人的真实姓名或校名；
3. 词数70个左右（开头已给出，不计入总词数）。
Is Space Exploration Worthwhile?
Here is the result of our discussion on whether space is worth exploring.
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