When the man first learnt how to make a fire, he began to use fuel for the first time. The first fuel he used was probably wood. As time passed, man (17)__________ discovered substances such as coal and oil. Coal was used very widely as a (18)__________ of energy until the end of the 19th century. (19)__________ the coming of the industrial revolution, it was soon realized that production (20)__________ if coal was used instead of wood. Nowadays, many of the huge factories and electricity generating stations would not be able to function if there was no coal.
In the last forty or fifty years; (21)__________, the use of coal has declined. As a result, there (22)__________ changes in the coal industry. It is believed that more people would use coal if oil and gas were not readily available.
- A. effectively B. locally C. eventually D. rapidly
- A. form B. source C. supply D. consumer
- A. As B. For C. With D. From
- A. would double B. will double C. doubles D. had doubled
- A. however B. therefore C. as a result D. as well as
- A. are B. were C. will be D. have been
