our rooms warm and moves cars,ships,planes and so on. And also oil gives us many useful things such as clothes and plastics.
(1)energysources (2)usefulthings (3)oil

2 But we have some problems about using oil at the same time. For example,gases from cars and factories cause the greenhouse effect and acid rain.They damage the earth.It is not so easy to stop them.But we must try
(1)some problems (2)greenhouse(3)acidrain

(2)トピック・センテンスとその位置
パラグラフは1つのトピックに関連する幾つかの文から構成されていますが、そのうちトピックを含む中心となる文はトピック・センテンスと呼ばれています。トピック・センテンスは文字通りそのパラグラフのトピックの提示を行なう重要な文ですから、このトピック・センテンスを探しだせば、そのパラグラフの要旨をほぼつかめることになります。
トピック・センテンスの位置は一般にはパラグラフの1）最初、2）末尾、3）内部の3箇所のいずれかになりますが、パラグラフの最初にくる場合が最も多いのです。

〈問題〉次の1〜3のパラグラフのトピック・センテンスはどれですか。
1　My sister is working in a village in Bangladesh. She helps farmers there. They want to increase food production by growing new kinds of rice.She studied farming when she was in college, so she can give them useful advice. She said in a letter,”I still don't speak the language well,but I enjoy working with my new friends here.”

2 My sister is one of many overseas volunteers from Japan. These days more and more young people join the JOCV or NGOs to share their knowledge and skills with people in other parts of the world. Very often I ask myself,"What can I do?"Then I think of the world in the 21stcentury.What will it be like ? The future may not be bright.

3 Take the population,for example. There are 5.6 billion people in the world now. There will probably be 10 billion by 2050.How can we produce enough food for us ? What can we do with all the waste we'll produce ? These are problems for the whole world. Each of us must do something.