题目内容：

阅读下面短文，在空白处填入1个适当的单词或括号内单词的正确形式。

Antarctica is one of the last real wildernesses 1. (leave) on the earth. Since it was first explored in the late 19th and early 20th centuries, various countries 2. (try) to use it for different purposes.

However, in 1961, 12 countries agreed to sign the Antarctic Treaty. This means that the entire area was 3. nuclear-free zone and could only be used for 4. (peace) purposes. Antarctica became the biggest laboratory in the world, with many scientists 5. (conduct) research there. Today 42 countries have signed the treaty, and have sent scientists to study in the area. Every summer, 3,000 scientists arrive to carry out a variety of research 6. (project).

Unlike the Arctic in the north, 7. is just made up of ice, Antarctica is an actual land mass. In fact, it is one 8. (ten) of the land surface of the earth. Over 140 million years ago, Antarctica was a green and living place. However, the land mass 9. (gradual) moved to the colder areas in the South, and now it is just as frozen as the Arctic.

Tourism has finally reached the great frozen wilderness. People come to see the local bird life, to go mountaineering, or to visit the South Pole. 10. we are not careful, it will not remain a wilderness for much longer.