3．Have you ever looked toward the sky on a fall day and witnessed a group of migrating birds？If so，you probably noted the V-shaped formation of the birds or the birds flying in a ball-like formation．Why do birds fly this way？Many theories have been developed to explain the formation patterns of different types of birds．
One theory is that birds fly in certain formations to take advantage of the laws of nature．The birds know that flying in a V-shaped pattern will save energy．Like the lead cyclist in a race who decreases wind force for the cyclists who follow，the lead bird cuts wind force for the birds that follow．This decrease in wind force means that the birds use up to 70percent less energy during their flight．When the lead bird becomes tired，a more rested bird takes over that position．
But saving energy is important for more than one reason．Sometimes food is short during migration flights．Keeping energy enables the birds to fly longer distances between meals．
When food is sighted，the birds guide one another in a different way．When a bird identifies a familiar feeding area，it might turn around in order to signal the group to change direction．Then，this bird becomes the new leader．It helps guarantee that other birds will know exactly where it is going．Then the whole group makes a change in direction，gently streaming from the sky down to the ground．This formation is like an arrow pointing to the location of food．
Scientists have also studied the birds that sometimes fly in a ball-like formation．Researchers believe that the birds come together if a predator （天敌） is spotted．The predator may then become impatient waiting for a single bird to fly away from the group．The birds will often dip and dive as a group，frustrating even the most persistent enemy．Scientists report that this is a very effective method of defense against an attack．
The birds care for their fellow fliers through teamwork．As transportation expert Henry Ford once said，"If everyone is moving forward together，then success takes care of itself．"When it comes to teamwork，these feathered fliers are a soaring success!
43．According to the passage，we can learn that birdsC．
A．move faster than cyclists
B．are smarter than other animals
C．play different roles in a formation
D．prefer to fly in a V-shaped formation
44．When food is sighted，A．
A．the group follows the discoverer
B．the lead bird decides what to do
C．the discoverer leaves the group
D．the whole group forms a stream
45．To protect themselves from attack，birds willD．
A．break into groups B．come close together
C．change directions D．fly up and down
46．Which is the best title for the passage？A
A．A Bird's-Eye View Of Teamwork
B．Success Takes Care Of Itself
C．The Strongest Will Survive
D．A Science Behind Flying．
分析 文章主要是从鸟儿整体的角度去分析它们各种习性，要凸显出它们的团队合作精神．
解答 CADA
43 C 文章没有提到迁徙的鸟比骑自行车的人快．根据第一段you probably noted the V-shaped formation of the birds or the birds flying in a ball-like formation．可知B不正确．D文章没有提到．通读文章可知在队形中各有各的职责．故答案选C．
44 A 根据第四段中When a bird identifies a familiar feeding area，it might turn around in order to signal the group to change direction．Then，this bird becomes the new leader．可知哪只鸟发现了食物就会成为新的领头者．故答案选A．
45 D 根据第五段可知当鸟类遇到其他动物的袭击的时候会选择像球形的形状．The predator may then become impatient waiting for a single bird to fly away from the group．这样它们的敌人就不容易袭击它们．故答案选D．
46 A 根据最后一段可知作者讲鸟类的团结合作，是为了让我们从中得到启示，故答案选A．
点评 考察学生的细节理解和推理判断能力，做细节理解题时一定要找到文章中的原句，和题干进行比较，再做出正确的选择．在做推理判断题不要以个人的主观想象代替文章的事实，要根据文章事实进行合乎逻辑的推理判断．
