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问题 选择题

暖水瓶的瓶胆夹壁中是真空，小明想利用它来探究真空能否传声，他把音乐贺卡里的电子发生器放入瓶中，根据听到的声音进行判断。在他设计的下列几组比较因素中最合理的是

A．塞上瓶塞和不塞瓶塞进行比较

B．把瓶胆放在近处和远处进行比较

C．用一个完好的和一个已经漏气的瓶胆进行比较

D．将音量大小不同的芯片先后放入瓶胆中进行比较

答案

答案：C

题目分析：A、塞上瓶塞和不塞瓶塞都是在同一个瓶胆里面，完好的瓶胆夹壁中都是真空的，有可能都听不到声音，无法比较；所以A错误；

B、把瓶胆放在近处和远处进行比较，还是在同一个瓶胆里面，有可能都听不到声音；所以B错误；

C、完好的瓶胆夹壁中都是真空的，漏气的瓶胆不是真空的，可以验证真空能否传声，所以C正确；

D、将音量大小不同的芯片先后放入瓶胆中，如果瓶胆是完好的，都不会听到声音，无法比较，所以D错误．

所以选C．

点评：我们的目的就是为了验证真空能否传声，所以我们需要比较的是真空和非真空条件下，物体发出的声音，我们是否能听到，需要选取的器材应该一个是真空条件下的，另一个是非真空条件下的．

单项选择题

Questions from 36 to 40 are based on the following passage: China’s trade volume surged in 2010. The development wasn’t only in quantity, but also in quality — namely structure diversification.The European Union, the United States and Japan remained China’s top 3 largest trading partners in 2010.But trade volumes between China and other emerging economies increased also. Bilateral trade volumes between China and other BRIC nations — Brazil, Russia and India — all jumped more than 40 percent. That made India China’s tenth largest trading partner.Huang Guohua, Statistics Department Director of General Administration of Customs said “Trade volume between China and emerging economies increased faster than that with the traditional market. It indicates that China’s foreign trade is diversifying, and showing less dependence on the traditional partners. It’s a good way to reduce risks.”Data also shows that foreign trade volumes developed dramatically in China’s middle and western areas last year. Although the southern province of Guangdong still topped others in the total volume of import and export.Huang Guohua said “The export volume of middle and western areas surged over 40 percent year on year in 2010. The speed was 10 percentage points higher than the country’s total. It indicates that industrial structure has improved in these areas.”The import and export volume of private enterprises surged faster than the country’s average in 2010, with 47 percent year on year growth. Experts say China’s foreign trade development reduced dependence on foreign-funded enterprises.2010 imports and exports reached a historical high with a p sign that the country’s trade sector has shrugged off the global economic recession.

According to the passage, what does the word “BRIC ” mean （）

A．Brazil, Russia , India and China

B．Britain, Romania , Italy and Canada

C．Bulgaria, Russia , Indonesia and Colombia

D．Belgium, Romania , Israel and Cuba
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多项选择题

沉香主要含的化学成分为

A．生物碱类

B．蒽醌类

C．挥发油

D．黄酮类

E．树脂
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