阅读下面短文, 根据短文内容, 完成下列各题。
In the 1930s, Saudi Arabia was one of the poorest countries in the world, but the discovery(发现)of oil changed this, and now it has become one of the world's richest countries.
America is now the world's biggest producer of oil and gas(燃气). However, it still buys a lot of oil from other countries, because it is the country that uses the most oil in the world as well. In fact, oil provides about one third of the world's energy.
By 2040, the world's energy use will increase about 30%. The clean energy must be used more if humans want to avoid weather change and serious global(全球)warming,
China is the world's largest user of coal(煤) and the second largest user of oil, but it also leads the world in clean energy. One third of the world's new wind power and solar panels(太阳能电池板)are in China, so it makes China become the biggest country which uses clean energy around the world. Also, it sells more electric cars than any other country.
We will run out of oil in the world, so it's necessary for us to turn to clean energy. Of course, the change will face new challenges. For example, it is very expensive to develop clean energy. Another challenge is that the wind and the sun are intermittent(间歇的). So powerful storage batteries(蓄电池)are needed to keep the energy for later use.
To stop global warming, we must develop clean energy and the world needs to work together closely.
