阅读短文，回答问题
William Kamkwamba lives in Malawi, Africa, where most people have to grow their own food and have no electricity or running water. When he was 14 years old, there was a terrible drought (干旱) and most families, including William's, couldn't grow enough food.
Because of the drought, William's family couldn't afford to send him to school any more. So one day, William went to the library near his home to study. He found a science book called Using Energy, which included instructions for building a windmill (风车). Windmills are good sources of electricity, and they can bring water up from underground. William didn't know much English, and he wasn't able to understand most of the book, but it was full of pictures. Looking at the pictures, William thought he could build a windmill for his family.
When William started building his windmill, a lot of people laughed at him, including his mother. But William saw the photo of the windmill in the book. That meant someone else was able to build it, so he knew he could build it, too. He didn't have the parts and equipment that he saw in the book's pictures. So he looked for parts in junkyards to build his machine.
William changed his design little by little. First, the windmill powered only one light bulb (灯泡). Finally, it powered four lights. Then there was enough electricity for four lights and a radio. No one laughed at William after that, and people in his town started to come to his house to get power for their cellphones. Later, William built a second windmill. This one brought water up from underground. After that, William began to teach other people how to build windmills.
Now he uses his website, movingwindmills.org to educate and give hope to people. His main message is this：To the Africans and the poor who are struggling (挣扎) with your dreams ...trust yourself and believe. Whatever happens, don't give up.
