求解逻辑题

Candycatgmat

还想请教TX几道逻辑题， TKS！

1）Twenty percents of all energy consumed in the United States is consumed by home appliances. If appliances that are twice as energy-efficient as those currently available are produced, this figure will eventually be reduced to about ten percent.

The argument above requires which of the following assumption?

A. Home-appliance usage would not increase along with the energy efficiency of the appliances.

B. It would not be expensive to produce home appliance that are energy-efficient.

C. Home-appliance manufacturers now have the technology to produce appliances that twice as energy-efficient as those currently available.

D. The cost of energy to the consumer would rise with increase in the energy efficiency of home applicances.

E. The percentage of energy consumed by home appliances will increase if existing appliances are not replaced by more energy-efficient models.

2) Oxygen-18 is a heavier-than-normal isotope of oxygen. In a rain cloud, water molecules containing oxygen-18 are rarer than water molecules containing normal oxygen. But in rainfull, a higher propotion of all water molecules containing oxygen-18 than of all water molecules  containing ordinary oxygen descends to earth. Consequently, scientists were suprised when measurement along the entire route of rain clouds' passage from above the Atlantic Ocean, the site of their original formation, across the Amazon forests, where it rains almost daily, showed that the oxygen-18 content of each of the clouds remained fairly constant.

Which one of the following statements, if true, best helps to resolve the conflict between scientists' expectations, based on the known behavior of oxygen-18, and the result of their measurements of the rain clouds' oxygen-18 content?

A. Rain clouds above tropical forests are poorer in oxygen-18 than rain clouds above unforested regions

B. Like the oceans, tropical rain forests can create or replenish rain clouds in the atomsphere above them

C. The amount of rainfall over the Amazon rain forest is exactly the same as the amount of rain originally collected in the clouds formed above the Atlantic Ocean.

D. The amounts of rain recycled back into the atmosphere from the leaves of forest vegetation is exactly the same as the amounts of rain in river runoffs that is not recycled into the atmosphere.

E. Oxygen-18 is not a good indicator of the effect of tropical rain forests on the atmosphere above them.

caixinni

1.A    2.B
请问楼主哪里不明白？

Candycatgmat

第一题现在明白了，只需考虑energy consumed 变化的条件，而不要被电费混淆。
第二题题目看不太懂，看不出问题在哪？科学家的理论和实际测量的矛盾是什么呢？

caixinni

题目中说在降雨云里面重水的含量比普通水的含量低。 但是在降水当中重水含量很高， 也就是说在降水的过程中，降雨云里的重水含量会降低。 但是实际测量当中，一整天都在降水的Amazon forests上空的云中 重水的含量 和 形成降雨云的地方Atlantic Ocean上空的云中 重水的含量 都没有变。 也就是说，在Amazon forests，降水过程中cloud里面失去的重水，又通过某种方式回到cloud里面了。 而B指出，热带雨林也能想海洋那样在它上空形成降雨云， 从而帮助解释了题目中所提到的conflict 。

这道题好长～分析起来也有点绕，感觉有点超出GMAC的出题水平了。。。

Candycatgmat

万分感谢！