Read the following passage and answer the question:         The world's oceans are so vast that they can cope with the present level of population. however, little is know about the long-term effects of such slow poisoning. the most serious problem of morden time is that man is destroying the earth's  natural and tranforming huge areas into waste land. as a result , it is becoming extremely defficult to grow enough to feed the world's increasing population. a way of protecting all wild life on the earth must also be found as many species are in danger of disappearing completely from the face of the earth. the smoke in th atmosphere , for exemple , is increasing so much that the amount of sunlight has been reduced in any cities. man's whole enviroment is being changed in a serious way.  1. what is the process of making something dirty?  2.find a word or phrase from the passage with the same meaning as the air, water and land in which we live? 3.what is the air surrounding the earth called? 4.what the could be best replaced wealth, goods or products people can use ? 5.what is the difficulty which needs attention and thought?