完形填空Rescue PlatformIn the aftermath of the terror

完形填空

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________(51)is a plat-form capable of flying vertically and hovering in the air_________(52)a helicopter. The plafform would rise up and down alongside a skyscraper and pick up people_________(53)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, _________(54)the Eagle,calls for two jet engines that_________(55)four large horizontal pro-pellers. The spinning of the propellers_________(56)the necessary lift,or upward force,to raise the platform. The more_________(57)is supplied to the propellers,the higher the platform _________(58).Moving the platform sideways involves_________(59)differing amounts of power to each propeller.

Helicopters are now used in some________(60)to get people out of burning buildings.Es-cape baskets slung from them dangle beside the building for people to climb into._________(61),the baskets cannot reach every floor of a building_________(62)the ropes from which they hang become unstable_________(63)a certain length.

So far,Metreveli has built a small-scale model of the Eagle to_________(64)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,_________(65)he calls the Eaglet.

51._________

A.. idea

B..skill

C. building

D..improvement