题目内容：

Man has been on the earth about one million years. He_1.   (manage) to live on every part of the planet, even though some climates have made life difficult. It is thought 2. (different) in skin color are the result of climatic__3.  .(adapt). For example, people with skin colors of yellow, red, and olive, generally come from areas 4._ they have had to adapt to other climates. Man's size also seems to   5. (various) according to climate. People living in colder regions are generally larger than6._ living in hotter ones. This difference might be explained_7. the fact that big people have less skin compared to weight than do small people. The less skin a person has relative to his weight, the easier  8.   is for him to keep warm. As part of the natural environment, climate greatly affects human activities. Climate has a significant  9.    0n agriculture. Climatic factors restrict the kinds of crops that can be grown. Man changes his living habits in order to adjust to climate, but climate 10.   (change) as well, though more slowly. By learning more about his climate, man will find a way to adapt to or control it and live a more comfortable life.