One of the most important discoveries of the nineteenth century was a method (17)__________ using natural gas for cooking and heating. Large amounts of natural gas are (18)__________ in the United States, usually several thousand feet below the surface the earth. Natural gas is most often found in places where petroleum, the oil from (19)__________ gasoline is made, is found. Often the natural gas must be removed before the oil itself is reached.
For many years after natural gas was first discovered, it was thought to have no value. (20)__________, people began to understand its uses and to find ways of storing it and of moving it from place to place.
Today, natural gas is stored in large tanks and used for lighting, cooking and heating. In many ways natural gas is one of our finest fuels. It can be (21)__________ for cooking without making the room hot. It is cheap and can be moved (22)__________ from one place to another through long pipelines some of which are hundreds of miles in length.
- A. in B. of C. to D. from
- A. find B. finding C. to find D. found
- A. who B. whom C. which D. whose
- A. However B. Moreover C. Besides D. Therefore
- A. use B. using C. to use D. used
- A. easily B. easy C. easier D. easiest
