Rescue Platform In the aftermath of the terrorist attacks on the World Trade Center, security experts are trying to develop

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问题                             Rescue Platform
    In the aftermath of the terrorist attacks on the World Trade Center, security experts are trying to develop new ways of rescuing people from burning skyscrapers. One【C1】______is a platform capable of flying vertically and hovering in the air【C2】______a helicopter. The platform would rise up and down alongside a skyscraper and pick up people【C3】______in high stories.
    The idea for the vertical takeoff platform was hatched(策划)more than ten years ago by a Russian aerospace engineer, David Metreveli, who has since moved to Israel. Metreveli’s design, 【C4】______the Eagle, calls for two jet engines that【C5】______four large horizontal propellers. The spinning of the propellers【C6】______the necessary lift, or upward force, to raise the platform. The more【C7】______is supplied to the propellers, the higher the platform【C8】______. Moving the platform sideways involves【C9】______differing amounts of power to each propeller.
    Helicopters are now used in some【C10】______to get people out of burning buildings. Escape baskets slung from them dangle beside the building for people to climb into. 【C11】______, the baskets cannot reach every floor of a building 【C12】______the ropes from which they hang become unstable【C13】______a certain length.
    So far, Metreveli has built a small-scale model of the Eagle to【C14】______his idea. In the wake of September 11 , he has been able to secure enough funding to start building a larger , 4-meter by 4-meter prototype, 【C15】______he calls the Eaglet.
【C11】

选项 A、Unfortunately
B、Uncertainly
C、Unimportandy
D、Unexpectedly

答案A

解析 空后一句说,由于悬挂救生篮的绳索在超出一定长度后就会非常不稳定,所以救生篮无法到达每一层楼。显然,这对于救援来说是一种不幸(Unfortunately)。故本题选A。
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