Many Americans feel that saving the world’s tropical forests warrants about as much concern as the snail darter. In Europe and the United States, they say, (11) d_____ n was the inevitable and desirable consequence of economic progress； why, therefore, should it be any different in the largely underdeveloped nations where the world’s tropical forests are to be found?

        The tropical forest is a biological warehouse. Estimates of the total number of species on the planet range up to 30 million, (12)_______ which only 1.6 million have been identified. It is further estimated that tropical forests, while occupying only 7 percent of the earth’s surface, may contain as many as half of all the earth’s forms of life. This means that only a tiny fraction of all tropical forest species has so far been studied and (13) d     e the drug industry’s increasing reliance on computer modeling, genetic engineering and other laboratory devices, concerned biologists regard the heedless squandering of the tropical forests’ known and unknown resources as a major tragedy. 

        Similarly, we depend on a small group of plants – corn, rice, wheat and the like – (14)         a large part of our sustenance. From time to time, plant pathologists have found, the commonly used strains of these plants require genetic fortification from the wild to protect them from (15) b      t and disease. Since many such plant originated in tropical areas and only later were cultivated elsewhere, the primeval forests of the tropics represent a vast genetic storehouse of great potential value to everyone.         Left untouched, tropical forests also contribute to the (16) s      y of the world’s climate. But when the forests are burned, the carbon released plays an important role in the (17) b      p of atmospheric gases producing the “greenhouse effect,” which is causing a warming trend on the planet. The consequences of this trend could be (18) p     d. America’s corn belt could become a subtropical region, while the melting of the polar ice cap could cause sea levels to rise and lead to drastic losses of coastal land.

 In (19) v        of all these factors, one might ask why the attack against the tropical forest continues so relentlessly. The answer is that even the infertile tropical forest is often capable of providing short-term economic benefits to individual and corporations. Given the human propensity to enjoy one last meal if the (20) a       e seems to be no meal at all, the present defoliation will probably continue unless a revolution in public and official attitudes – equivalent to the dramatic change of the 1980’s in how smoking is perceived and handled – comes to the rescue at the eleventh hour.