Copying Birds May Save Aircraft FuelBoth Boeing and Airbus have trumpeted the efficiency of their newest aircraft.The 787 and 350 respectively.Their clever designs and lightweightcompositescertainly make a difference.But a group of researchers at Stanford University,led by Ilan Kroo,has suggested that airlines could take a more naturalisticapproach to cutting jet-fuel use and it would not require them to buy newaircraft.The answer,says Dr Kroo,lies with birds.Since 1914,scientists have known thatbirds flying in formation-a V-shape-expend less energy.The air flowing over abird's wings curls upwards behind the wingtips.a phenomenon known asupwash.Other birds flying in the upwash experience reduced drag,and spendless energy propelling themselves.Peter Lissaman,anaeronautics expert whowas formerly at Caltech and the University of Southern California,has suggestedthat a formation of 25 birds might enjoy a range increase of 71%.When applied to aircraft,the principles are not substantially different.Dr Krooand his team modeled what would happen if three passenger jets departing fromLos Angeles,San Francisco and I as Vegas were to assemble over Utah,assume aninverted V-formation occasionally change places so all could have a turn in themost favourable positions,and proceed to London.They found that the aircraftconsumed as much as 15%less fuel（coupled with a reduction in carbon-dioxideoutput）.Nitrogen-oxide emissions during the cruising portions of the flight fellby around a quarter.There are,of course,knots to be worked out.One consideration is safety,or atleast the perception of it.Would passengers feel comfortable travelling incompanion?Dr Kroo points out that the aircraft could be separated by severalnautical miles,and would not be in the intimate groupings favoured by displayteams like the Red Arrows,A passenger peering out of the window might noteven see the other planes.Whether the separation distances involved wouldsatisfy air-traffic-control regulations is another matter,although a working groupat the International Civil Aviation Organisation has included the possibility offormation flying in a blueprint for new operational guidelines.It remains to be seen how weather conditions affect the air flows that makeformation flight more efficient.In zones of increased turbulence,the planes'wakes will decay more quickly and the effect will diminish.Dr Kroo says this isone of the areas his team will investigate further.It might also be hard for airlinesto co-ordinate the departure times and destinations of passenger aircraft in a waythat would allow them to gain from formation flight.Cargo aircraft,in contrast,might be easier to reschedule,as might routine military flight.As it happens,America's armed forces are on the on case already.Earlier thisyear the country'S Defence Advanced Research Projects Agency announcedplans to pay Boeing to investigate formation flight,though the programme hasyet to begin.There are reports that some military aircraft flew in formation whenthey were low on fuel during the Second World War,but Dr Lissaman says theyare unsubstantiated."My father was an RAF pilot and my cousin the skipper of aLancaster lost over Berlin,"he adds.So he should know
The role that weather plays in formation flight has not yet been clearly defined.
正确
由题干关键词weather可推测答案依据在原文第五段第一句。题千the rolethe weather plays是原文信息句It remains to be seen how weather conditionsaffected the air flow的简要表达,而题干中的has not yet been clearly defined和原文的it remains to be seen意思是相同的。因而可以判断本句正确。答案为T.
解决人生目的和奋斗目标的问题，最根本的是要靠
理想作为对未来的向往和追求，是
理想的追求和实现是一个
爱国主义的基本要求是
强国必须强军。历史有力证明，落后就要挨打。没有国防和军队的现代化，就不会有国家的现代化，就不会有中华民族的伟大复兴。中共十九大对全面推进国防和军队现代化作出新的战略安排，包括
走军民融合式发展路子，是实现富国和强军统一的重要途径。军民融合，源于我们党的“军民结合、寓军于民”的思想，其目的就是在更广范围、更高层次、更深程度上把国防和军队现代化建设有机融入经济社会发展体系之中，做到一笔投资、双重效益。加快形成军民融合深度发展格局，要做到
构建中国特色现代军事力量体系是建设世界一流军队的力量基础。总体来说，就是要加快形成精干、联合、多能、高效的信息化军事力量体系，重点是优化作战力量结构，建设现代化陆军、海军、空军、火箭军、战略支援部队和武警部队，促进各军兵种力量协调发展。其中，我国战略威慑的核心力量是
人民军队必须牢牢坚持党对军队的绝对领导，把这一条当作人民军队永远不能变的军魂、永远不能丢的命根子，任何时候任何情况下都以党的旗帜为旗帜、以党的方向为方向、以党的意志为意志。党对军队的绝对领导，其基本内容是
坚持党对军队的绝对领导不是抽象的原则要求，而是有一整套制度作保证的。党对军队绝对领导的最高实现形式是
党的十九大报告指出，扎实做好各战略方向军事斗争准备，统筹推进传统安全领域和新型安全领域军事斗争准备，发展新型作战力量和保障力量，开展实战化军事训练，加强军事力量运用，加快军事智能化发展，提高基于网络信息体系的联合作战能力、全域作战能力，有效塑造态势、管控危机、遏制战争、打赢战争。军队是要准备打仗的，一切工作都必须
