Genetically modified (GM) (转基因的) crops have made an enormous positive influence on the world. In recent years, GM technology has brought much benefit directly to farms, reducing the use of poisonous chemicals that kill pests of plants, and reducing greenhouse gas emissions (排放)．

　　A particular concern among farmers in developing countries is the loss of crops to insect pests. One way to fight this problem is to use chemicals，but this behavior will do harm to the health of farmers, the environment, and the people who eat the food. Instead, biotechnology can be used to increase production of pest­resistant crops. For example, in Africa, the sweet potato serves as an important crop, but viruses (病毒) can dramatically destroy its output by up to 80%. The Kenya Agricultural Research Institute, however，has developed a genetically modified sweet potato that can increase crop production by 18­25%. What's more, this new kind of potato has genes that resist damage due to bad climate or unexpected natural disasters.

　　The use of genetically modified foods can have a positive effect on the economy, especially in less developed countries. GM crops have already led to economic growth in South Africa, according to some studies. Because GM crops require fewer chemicals, farmers can save money on both the costs of pesticides and labor necessary to manage the treatments. This, combined with higher output, allow the farmer to gain more from the product.

　　With an increasing adoption of GM crops, the use of pest­control chemicals has been greatly reduced. In fact, while not necessarily related to food­related biotechnology, some GM plants have been developed to take care of heavy metal pollution in some polluted soil. Finally, biotechnology can allow people to receive vaccines (疫苗) that are difficult to distribute. By putting vaccines into food products, organizations can more easily transport them to people in need.

　　1．We can learn from the text that________.

　　A．GM crops benefit the environment

　　B．farmers fail to grow a lot of plants

　　C．insect pests do less harm to the soil

　　D．more greenhouse gas is sent into the air

　　2．What can we infer from the example of the sweet potato?

A．Kenya will have the most advanced technology in the future.