Complete each space with one of the words given below

Part 6: Complete each space with one of the words given below. Make changes if necessary. (1,0 m)

since

soon

late

economic

pollute

exhaust

of

In humankind's millions (1)__________ years on earth, many types of energy resources have been utilised. However, in the last ninety years, petroleum has become by far the most important. Accounting for over 50 percent of all energy consumed, it is so essential that, without petroleum, we could be faced with (2)__________ disaster. Of course, the arth's supply of petroleum will not last forever, and in fact, it will disappear (3)__________ than most people believe. At the current rate of consumption, the world has proven oil reserves may be (4)__________ within forty or fifty years.