Read the passage and then do the tasks that follow.
(Đọc kĩ đoạn văn và sau đó làm các nhiệm vụ tiếp theo.)
At present, most of our energy comes from fossil fuels (oil, coal, and natural gas). However, such reserves are limited. Because power demand is increasing very rapidly, fossil fuels will be exhausted within a relatively short time. Therefore, people must develop and use alternative sources of energy.