单选题 The idea seems sort of foolish, just another exercise trick. Stand for a few minutes on a platform that vibrates. Get off and try to do some weight lifting. Or see how high you can jump. You are【C1】______supposed to be able to lift heavier weights and jump higher. But maybe it's not so【C2】______, exercise experts say. Although they don't really know why vibrations should work, researchers report that they actually seem to slightly improve【C3】______in the few minutes after a person gets off the machine. The problem,【C4】______, is that there is little【C5】______on how fast the vibrations should be or in what direction platforms are【C6】______to vibrate. Some studies have【C7】______to show any effects from vibrations. And then there is the question of【C8】______exactly vibrations are doing to muscles and nerves. "It【C9】______is arousing interest, and a large portion of the【C10】______would support that something is happening," said Lee E. Brown, an expert at California State University. But he added, "We are still trying to【C11】______exactly what the mechanism is." Meanwhile, several companies make the vibrating platforms, and they are being used at gyms and【C12】______some athletes. One company, Power Plate,【C13】______that stars like Serena Williams and Justin Morneau, of the Minnesota Twins, train with its【C14】______. Another company, Wave, says the United States ski team used its vibrating plates in training【C15】______the coming Winter Olympics. But researchers are【C16】______. "There is something to it," said William J. Kraemer, a professor at the University of Connecticut,【C17】______it "another tool" for athletic conditioning. But he added that other conditioning methods might【C18】______the same or better results. Researchers say, people should be appropriately skeptical about the effects of standing on a vibrating platform. "We don't know a lot about prescribing it," Dr. Kraemer said. "There's the【C19】______. Research is trying to【C20】______up."

【正确答案】 C

【答案解析】解析：上下文语义题。trying to“设法，尝试”后跟动词原形，根据空格后的宾语“(振动产生作用的)机制是什么”，再结合第二段提到的“研究人员不清楚振动能起作用的原因”，可推断“我们”是要设法弄清楚振动产生作用的机制，故C项figure out“弄明白”最适合句意，选C。

【正确答案】 A

【答案解析】解析：上下文语义题。该段首句提及有几家公司制作了振动机供健身房和一些运动员使用，此处则以一家叫Power Plate的公司作进一步的讲述，根据空格后that引导的宾语从句“诸如Serena Williams和Justin Morneau等明星都使用它的……进行训练”，推断这里是讲该公司宣布某事情，应用A项proclaim，意为“宣布，公布”，与下一句的says相对应。

【正确答案】 B

【答案解析】解析：上下文语义题及近义词辨析。该段首句的several companies和空格所在句中的one company是由总到分的关系，既然首句讲的是关于振动机(vibrating platforms)的使用问题，那么此处应该依旧讲振动机的使用情况，空格处的名词需能指代振动机。device指为某一特殊用途或解决某一特定机械问题而设计或改装的精巧的仪器或装置，振动机是为了运动而设计的装置，故device填入文中最贴切。

【正确答案】 A

【答案解析】解析：上下文语义题。句首的But表明本句与上文存在转折关系，上一段提到运动员用振动机来训练，暗示该仪器的确具有一定的效果，本句应与此意相反，且结合本段下文提到的“研究人员说人们应该对振动机的效果保持适当的质疑”(skeptical about)可知，本段内容是对振动机效果的怀疑，故填入A项alert，表示“研究人员很警惕”。