RCjj10关于solar pond那篇的题

以前hanvivien提供过文章，今天做GMATprep正好做到了，就把题目记下了，供大家分享。用alt+tab切换打出来的，应该不会有错误。

Solar ponds are bodies of water in which circulation is incomplete and there is a very high salt concentration that increases with depth.  This vertical change in salinity serve to trap heat because concentrated brine in the lowest water level acts as a collector and storage area for solar heat, while the less saline, lighter water at the upper levels provides insulation.  Heat is thus retained in the depths.
 An artificial pond of this type has been constructed on the western shore of the Dead Sea in Israel in order to test ints suitability as a source of low-grade heat for conversion into electricity.  An immediate threat to the success of the venture was the was the growth of algae.  Water in solar ponds must be kept maximally transparent to allow penetration of light to the deep storage area.  Therefore, any particles of matter in the water, such as algae cells, that scatter or absorb light will interfere with the collection of heat.
 One proposed method of the controlling the algae was the application of an algicide.  However, the Dead Sea is a closed body of water without any outlet and as such is very easily contaminated.  Extensive use of chemicals in numerous future full-scale solar ponds would lead to such contamination of the Dead Sea, which now enjoys a lucrative tourist trade.
 A recent experiment has supplied a more promising method for controlling the algae.  To repress the algae cells' capacity for accommodating themselves to environmental changes, the water in the solar pond was first made more saline through evaporation and then diluted by a rapid inflow of fresh water.  This shock reduced the cells' ability to regulate the movement of water through their membranes.  The rapidly absorbed water, resulting in distortions of shape, increase in volume, and impairment to motility.  Their buoyancy adversely affected, the cells sank to the bottom of the pond, where they encountered the hot waters of the storage layer and were destroyed.  This method allows for effective control of nuisance algae while leaving solar ponds as one of the cleanest technologies providing energy for human use.
33
According to the passage,the growth of algae was considered a threat to the success of the artifical pond near the Dead sea because the algae:
A： Produce excess oxygen that allows the water temperature in pond
B： Restrict the circulation of water within the pond
C： Enable heat to escape through the upper level of the pond
D： Prevent light from penetrating to the lowest levels of the pond
E： prevent accurate measurement of the heat collected in the pond
Answer
34
It can be inferred from the passage which of the following is true about the salinity and temperatures of the highest and lowest waters layer in a typical solar pond?
A： The bottom layer is both highly saline and quite hot,while the top layer is less saline and cooler
B： The two layers have the same saline levels,but the bottom layer is hotter than the top
C： There is no way to predict the salinity and temperature of the different water layers in different solar ponds
D： The bottom layer is less saline and quite hot,while the top layer is more saline and cooler
E： The top layer has both higher salinity and higher temperatures than the bottom layer
Answer:A
35
Which of the following,if true,would seriously undermine the validity of the conclusions drawn from the experiment described in the last paragraph of the passage?
A： The algae cells than sank to the bottom of the pond were destroyed only after a time lag of twenty-four hours
B： The lateral motility of the algae cells that sank to the bottom of the pond was not imparied
C： The water with which the artificial solar pond was diluted contained microorganisms that kill algae
D： The algae cells that sank to the bottom of the pond were actually killed by the rapid change in pressure
E： The higher salinity brought about through evaporation increased the transparency of the upper levels of water in the pond
Answer:C

36
The primary purpose of this passage is to:
A： Discuss ways of solving a problem that threatens to limit the usefulness of an energy source
B： Explain the mechanisms by which solar heat may be converted into energy
C： Detail the processed by which algae cells colonize highly saline bodies of water
D： Report the results of an experiment designed to clean contaminated bodied of water
E： Describe the unique properties of a solar pond on the edge of Dead Sea
Answer:A

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