Since 1965, when is equipment became operational, a device called Eros has been helped to make sky traffic__1__ safe. Eros is short for Eliminate Range Zero Systemrange zero meaning collision. Basically Eros is a computer system measures, with great speed and precision, closing__2__ speed ( the speed at which two objects are approaching each other ) and range ( the distance apart of the objects ).Eros can warn aircraft approachable each other at jet__3__ speeds and can provide protection for as many as a thousand aircraft in wide area. The pilot of an Eros−equipped aircraft heading for a collision hear a warning noise in his ear−phones__4_when his airborne computer calculates that he is within thirty seconds or half a mile ( whichever occurs first ) of other aircraft.__5__ At the same time, a flashing red arrow on the device's indicator panel instructs him to climb. Simultaneously, in the other aircraft, __6__ the signal is automatically reversed: the flashing arrow tells the pilot to climb. The newer Eros II system can accommodate a total of two thousands aircraft at one time within a 140−mile radius__7__ Every three seconds, each Eros−equipped plane automatically reports to ground stations and to similarly equipped aircraft their precise range, altitude and approach rate. The producers__8__ of Eros, the McDonnell Dougals Corporation in the U.S., are now studying the fitting of Eros and will do more to make__9__ the sky safer: they shall also lighten the work of air−traffic__10__ controllers and increase the efficiency of airports.
答案：
1. helped—helping.现在完成进行时
2. measures前加that/which.that/which引导定语从句，修饰先行词a computer system
3. approachable—approaching.approaching为现在分词，修饰aircraft，相当于that/which are approaching each other
4.hear—hears.其主语是the polit
5. other—another.相对于上提到的an Eros−equipped aircraft， 此处为另一架飞机
6. climb—descend.根据上下文的意义，一架飞机下降，另一架飞机上升，以免相撞
7.thousands—thousand.根据语法规则，数词hundred 、thousand 、million等词一般为单数形式
8. their—its.指上文中的主语each equipped plane
9. 去掉make前的to.do与make并列作动词谓语
10. shall—will.表示一般将来，shall常用于第一人称，will则常用于第二和第三人称
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