when the man first learns how to make a fire he began to use fuel for the first time the first foel he used was probably wood as time passed man eventually discovered that substances such as coal and oil(1) coal(2) very widely as a source of energy until the end of the 19th century with the coming of the industrial revolution it was soon realized that production(3) if coal was used instead of wood nowadays many of the huge factories and electricity generating stations (4) to function if there was no coal in the last forty or fifty years however the use of coal(5) as a result there have been changes in the coal industry it(6) that more people(7) coal if oil and gas were not readily available there is more than enough coal in the world for man's needs for the next two hundred years if our use of coal(8) unfortunately however about half of the world's coal(9) mining much of it(10) very expensive even if it was possible to use new equipment 1)A are burning B would bum C have burn D were burnt 2) A not used B did not use C not using D was not used 3) A doubles B had doubled C will double D would double 4) A were unable B would be unable C will be unable D are unable 5)A has declined B will decline C declines D would declines 6) A believed B is believing C believing D is believed 7) A would use B used C use D will use 8) A did not increase B would not increase C does not increase D May not increase 9) A would never use B may never be used C may never use D would never be used 10)A was B used to be C would be D has been