标题: 求助PREP逻辑一道 [打印本页] 作者: alanuonuo 时间: 2010-8-5 04:40 标题: 求助PREP逻辑一道 Although fullerenes-spherical molecules made entirely of carbon-were first found in the laboratory, they have since been found in nature, formed in fissures of the rare mineral shungite. Sine laboratory systhesis of fullerenes requires distinctive conditions of temperature and pressure, this discovery should give geologists a test case for evaluating hypotheses about the state of the Earth's crust at the time these naturally occuring fullerenes were formed. Which of the following, if ture, most seriously undermines the argument? A Cinfirming that the shungite genuinely contained fullerenes took careful experimentation. B Some fullerenes have also been found on the remains of a small meteorite that collided with a spacecraft. C The mineral shungite itself contains large amounts of carbon, from which the fullerenes apprently formed. D The naturally occurring fullerenes are arranged in a previously unknown crystalline structure. E Shungite itself is formed only under distinctive conditions.
13. (26741-!-item-!-188;#058&002910) Which of the following most logically completes the argument?
United States manufacturers currently produce most of the world's solar-power generators--most of which are exported to Europe. However, European manufacturers are emerging and probably will ultimately capture much of the European market. The United States government is funding initiatives intended to encourage use of solar power within the United States. If these initiatives succeed in increasing the demand for solar-power generators in the United States, United States manufacturers will probably maintain significant production levels, since __________.
(A) some United States manufacturers have been substantially increasing their output over the last several years (B) the efficiency of solar-power generators in converting energy from the Sun into electric power is not improving as fast as it once did (C) just as European manufacturers enjoy certain competitive advantages in Europe, so do United States manufacturers in the United States (D) European governments are currently undertaking initiatives to stimulate the use of solar power within Europe (E) the current market for solar-power generators in the United States is very limited