Read the following passage and choose the correct answer. Coal is a black solid fossil fuel. It is usually very hard. Coal is made of 65%-95% carbon. It also has hydrocarbons and some other compounds in it. It is (23) ____ from the remains of plants(24) ____ lived millions of years ago. Coal can be burned for energy or electricity. Burning it is not as common as it used to be, (25) ____ it causes much pollution. Natural gas is a mixture. It consists mainly of hydrocarbons. The main component is methane. Natural gas is often found in the ground together with petroleum. Most natural gas is burned directly to produce energy. It burns with a clean blue flame. It causes (26) ____ pollution. The main use of natural gas is to produce electricity. It is also used as fuel for cars, cooking gas and to make fertilizers. 23. A.formed B. done C. founded D. made 24. A. who B. that C. whose D. why 25. A. because B. but C. therefore D. however 26. A. few B. little C. many D. a lot