All too often, a choice that seems sustainableturns out on closer examination to

All too often, a choice that seems sustainable(可持续的)turns out on closer examination to be problematic.Probably the best example is the rush to produce ethanol(乙醇) for fuel from corn. Corn is a renewable resource—you can harvest it and grow more, almost limitlessly. So replacing gas withcorn ethanol seems like a great idea. 

   One might get a bit more energy out ofthe ethanol than that used to make it, which could still make ethanol moresustainable than gas generally, but that’s not the end of the problem. Usingcorn to make ethanol means less corn is left to feed animals and people, whichdrives up the cost of food. That result leads to turning the fallow land–including, in some cases, rain forest in places such as Brazil—into farmland,which in turn gives off lots of carbon dioxide (CO) into the air. Finally, overmany years, the energy benefit from burning ethanol would make up for theforest loss. But by then, climate change would have progressed so far that itmight not help.

   You cannot really declare any practice“sustainable” until you have done a complete life-cycle analysis of itsenvironmental(环境的) costs. Even then, technology and publickeep developing, and that development can lead to unforeseen and undesiredresults. The admirable goal of living sustainably requires plenty of thought onan ongoing basis.

1.What might directly cause the loss of the forestaccording to the text?

A. The growing demand for energy to make ethanol

B. The increasing carbon dioxide in the air

C. The greater need for farmland

D. The big change in weather.

2.The underlined word “it” in the second paragraphrefers to “           ” 

A. the energybenefit                                             B.the forest loss 

C. climatechange                                          D.burning ethanol 

3.The author thinks that replacing gas with cornethanol is           . 

A.impractical                    B.acceptable               C.admirable         D. useless 

4.What does the author mainly discuss in thetext? 

A. Technology                          B.Sustainability

C. Ethanol energy            D.Environmental protection 

试题答案

【答案】

1.C

2.A

3.A

4.B

【解析】

试题