1 . 阅读下面短文，在空白处填入适当的内容（1个单词）或括号内单词的正确形式。

There is no doubt that humankind dreams of making Mars our second home. However, sending people there will require all the skills, courage and     1     (intelligent) of the human race. While the Moon can be reached within days, it would take months to reach Mars,     2     (travel) through dangerous solar radiation. And even if the first settlers do reach Mars safely, staying alive will be     3    daily challenge, but as proved by the Biosphere experiment, not impossible.

As early as the 1980s, scientists were building Biosphere 2 in the Arizona desert. It consisted of a closed space    4     people, animals and plants could live together. The “closed” concept meant that the space was designed     5     (function) with its own oxygen, food and water, needing nothing from the outside world.     6     the two-year experiment was not a success, it did provide us with a better understanding of how humans might be able to live on another planet. More recently, scientists     7     (succeed) in growing a variety of plants in an environment similar to that on Mars. That     8     (definite) is a big step forward.

For now, human settlement of Mars is still     9     (decade) away. In the meantime, scientific research shows that the planet Earth is getting     10     (warm). This change is having a terrible effect on the biosphere.