阅读理解。 People all over the world cat rice.Millions of people in Asia  Africa and South America eat it every day of their lives. Some people eat almost nothing but rice. Rice is a kind of grass. There are more than 7, 000 kinds of rice. Farmers grow rice in many countries, even in the South part of the United States think that is started to grow in two places. They think that one kind of rice grew in Southern Asia thousands of years ago. Someone in China wrote about it almost 5, 000 years ago. Another kind probably grew in West Africa. Other scientists think that rice came from India, arid Indian travelers took it to other parts of the world. These are two main ways to grow rice. Most rice grow in wet soil. People in many countries do all of the work of growing rice by hand. This is the same way farmers worked hundreds of years ago. In some countries,  people now use machines on their rice farms. People use every part of the rice plant. They make animal feed and rice oil from it. They also make baskets,  brooms and roofs for their houses. They burn dry rice plants in fires for cooking. 根据短文内容，回答下列问题。 1. How many kinds of rice came from? __________________________________________ 2. Where do scientists think rice came from? __________________________________________ 3. How did farmers grow rice hundreds of years ago? __________________________________________ 4. Which part of the rice plant can be used! __________________________________________ 5. What do you think is the best way to grow rice? __________________________________________