篇一：关于斜拉桥的英文
Study on nonlinear analysis of a highly redundant cable-stayed bridge
1．Abstract
A comparison on nonlinear analysis of a highly redundant cable-stayed bridge is performed in the study. The initial shapes including geometry and prestress
distribution of the bridge are determined by using a two-loop iteration method, i.e., an equilibrium iteration loop and a shape iteration loop. For the initial shape analysis a linear and a nonlinear computation procedure are set up. In the former all
nonlinearities of cable-stayed bridges are disregarded, and the shape iteration is carried out without considering equilibrium. In the latter all nonlinearities of the bridges are taken into consideration and both the equilibrium and the shape iteration are carried out. Based on the convergent initial shapes determined by the different procedures, the natural frequencies and vibration modes are then examined in details. Numerical results show that a convergent initial shape can be found rapidly by the two-loop iteration method, a reasonable initial shape can be determined by using the linear computation procedure, and a lot of computation efforts can thus be saved. There are only small differences in geometry and prestress distribution between the results determined by linear and nonlinear computation procedures. However, for the analysis of natural frequency and vibration modes, significant differences in the
fundamental frequencies and vibration modes will occur, and the nonlinearities of the cable-stayed bridge response appear only in the modes determined on basis of the initial shape found by the nonlinear computation.
2. Introduction
Rapid progress in the analysis and construction of cable-stayed bridges has been made over the last three decades. The progress is mainly due to developments in the fields of computer technology, high strength steel cables, orthotropic steel decks and construction technology. Since the first modern cable-stayed bridge was built in Sweden in 1955, their popularity has rapidly been increasing all over the world. Because of its aesthetic appeal, economic grounds and ease of erection, the
cable-stayed bridge is considered as the most suitable construction type for spans ranging from 200 to about 1000 m. The world’s longest cable-stayed bridge today is the Tatara bridge across the Seto Inland Sea, linking the main islands Honshu and
Shikoku in Japan. The Tatara cable-stayed bridge was opened in 1 May, 1999 and has a center span of 890m and a total length of 1480m. A cable-stayed bridge consists of three principal components, namely girders, towers and inclined cable stays. The girder is supported elastically at points along its length by inclined cable stays so that the girder can span a much longer distance without intermediate piers. The dead load and traffic load on the girders are transmitted to the towers by inclined cables. High tensile forces exist in cable-stays which induce high compression forces in towers and part of girders. The sources of nonlinearity in cable-stayed bridges mainly include the cable sag, beam-column and large deflection effects. Since high pretension force exists in inclined cables before live loads are applied, the initial geometry and the prestress of cable-stayed bridges depend on each other. They cannot be specified independently as for conventional steel or reinforced concrete bridges. Therefore the initial shape has to be determined correctly prior to analyzing the bridge. Only based on the correct initial shape a correct deflection and vibration analysis can be achieved. The purpose of this paper is to present a comparison on the nonlinear analysis of a highly redundant stiff cable-stayed bridge, in which the initial shape of the bridge will be determined iteratively by using both linear and nonlinear computation procedures. Based on the initial shapes evaluated, the vibration frequencies and modes of the bridge are examined.
3. System equations
3.1. General system equation
When only nonlinearities in stiffness are taken into account, and the system mass and damping matrices are considered as constant, the general system equation of a finite element model of structures in nonlinear dynamics can be derived from the Lagrange’s virtual work principle and written as follows:
Kjbαj-∑Sjajα= Mαβqβ”+ Dαβqβ’
3.2. Linearized system equation
In order to incrementally solve the large deflection problem, the linearized
system equations has to be derived. By taking the first order terms of the Taylor’s expansion of the general system equation, the linearized equation for a small time (or load) interval is obtained as follows:
MαβΔqβ”+ΔDαβqβ’ +2KαβΔqβ=Δpα- upα
3.3. Linearized system equation in statics
In nonlinear statics, the linearized system equation becomes
2KαβΔqβ=Δpα- upα
4. Nonlinear analysis
4.1. Initial shape analysis
The initial shape of a cable-stayed bridge provides the geometric configuration as well as the prestress distribution of the bridge under action of dead loads of girders and towers and under pretension force in inclined cable stays. The relations for the equilibrium conditions, the specified boundary conditions, and the requirements of architectural design should be satisfied. For shape finding computations, only the dead load of girders and towers is taken into account, and the dead load of cables is neglected, but cable sag nonlinearity is included. The computation for shape finding is performed by using the two-loop iteration method, i.e., equilibrium iteration and shape iteration loop. This can start with an arbitrary small tension force in inclined cables. Based on a reference configuration (the architectural designed form), having no deflection and zero prestress in girders and towers, the equilibrium position of the cable-stayed bridges under dead load is first determined iteratively (equilibrium iteration). Although this first determined configuration satisfies the equilibrium
conditions and the boundary conditions, the requirements of architectural design are, in general, not fulfilled. Since the bridge span is large and no pretension forces exist in inclined cables, quite large deflections and very large bending moments may
appear in the girders and towers. Another iteration then has to be carried out in order to reduce the deflection and to smooth the bending moments in the girder and finally to find the correct initial shape. Such an iteration procedure is named here the ‘shape iteration’. For shape iteration, the element axial forces determined in the previous step will be taken as initial element forces for the next iteration, and a new
equilibrium configuration under the action of dead load and such initial forces will be determined again. During shape iteration, several control points (nodes intersected by the girder and the cable) will be chosen for checking the convergence tolerance. In each shape iteration the ratio of the vertical displacement at control points to the main
span length will be checked, i.e.,
|vertical displacement at control points
main span|??
The shape iteration will be repeated until the convergence toleranceε, say 10-4, is achieved. When the convergence tolerance is reached, the computation will stop and the initial shape of the cable-stayed bridges is found. Numerical experiments show that the iteration converges monotonously and that all three nonlinearities have less influence on the final geometry of the initial shape. Only the cable sag effect is significant for cable forces determined in the initial shape analysis, and the
beam-column and large deflection effects become insignificant.
The initial analysis can be performed in two different ways: a linear and a
nonlinear computation procedure. 1. Linear computation procedure: To find the equilibrium configuration of the bridge, all nonlinearities of cable stayed bridges are neglected and only the linear elastic cable, beam-column elements and linear constant coordinate transformation coefficients are used. The shape iteration is carried out without considering the equilibrium iteration. A reasonable convergent initial shape is found, and a lot of computation efforts can be saved.
2. Nonlinear computation procedure: All nonlinearities of cable-stayed bridges are taken into consideration during the whole computation process. The nonlinear cable element with sag effect and the beam-column element including stability coefficients and nonlinear coordinate transformation coefficients are used. Both the shape iteration and the equilibrium iteration are carried out in the nonlinear
computation. Newton–Raphson method is utilized here for equilibrium iteration.
4.2. Static deflection analysis
Based on the determined initial shape, the nonlinear static deflection analysis of cable-stayed bridges under live load can be performed incrementwise or iterationwise. It is well known that the load increment method leads to large numerical errors. The iteration method would be preferred for the nonlinear computation and a desired convergence tolerance can be achieved. Newton– Raphson iteration procedure is employed. For nonlinear analysis of large or complex structural systems, a ‘full’iteration procedure (iteration performed for a single full load step) will often fail. An increment–iteration procedure is highly recommended, in which the load will be
incremented, and the iteration will be carried out in each load step. The static deflection analysis of the cable stayed bridge will start from the initial shape
determined by the shape finding procedure using a linear or nonlinear computation. The algorithm of the static deflection analysis of cable-stayed bridges is summarized in Section 4.4.2.
4.3. Linearized vibration analysis
When a structural system is stiff enough and the external excitation is not too intensive, the system may vibrate with small amplitude around a certain nonlinear static state, where the change of the nonlinear static state induced by the vibration is very small and negligible. Such vibration with small amplitude around a certain nonlinear static state is termed linearized vibration. The linearized vibration is different from the linear vibration, where the system vibrates with small amplitude around a linear static state. The nonlinear static state qα can be statically determined by nonlinear deflection analysis. After determining qαa , the system matrices may be established with respect to such a nonlinear static state, and the linearized system equation has the form as follows:
MαβAqβ”+ DαβAqβ’+ 2KαβAqβ=pα(t)- TαA
where the superscript ‘A’ denotes the quantity calculated at the nonlinear static state qαa . This equation represents a set of linear ordinary differential equations of second order with constant coefficient matrices MαβA, DαβA and 2KαβA. The equation can be solved by the modal superposition method, the integral transformation methods or the direct integration methods.
When damping effect and load terms are neglected, the system equation becomes
MαβAqβ” + 2KαβAqβ=0
This equation represents the natural vibrations of an undamped system based on the nonlinear static state qαa The natural vibration frequencies and modes can be obtained from the above equation by using eigensolution procedures, e.g., subspace iteration methods. For the cable-stayed bridge, its initial shape is the nonlinear static state qαa . When the cable-stayed bridge vibrates with small amplitude based on the initial shape, the natural frequencies and modes can be found by solving the above equation. a
篇二：英文 简要的黄鹤楼-古琴台-东湖-第一长江大桥介绍
Yellow Crane Tower
Bordering on the Yangtze River and crouching on
the top of the Snake Hill, the Yellow Crane Tower
is one of the three most famous towers on the
south bank of the Yangtze River. (the other two are Yueyang Tower in Hunan and Tengwang Tower in Jiangxi)
First built in 223 AD, the tower has a history of over 1700 years. It is not only an important scenic spot, but also a symbol of "piping times of peace" in people's minds. Scholars in the past dynasties wrote hundreds of poems and scores of writings in praise of the magnificent Yellow Crane Tower. The legend about the tower has become a bright pearl of the Chinese literature.
Rebuilt in 1985, the Yellow Crane Tower Park occupies a hilly area and consists of towers, pavilions and corridors, forming an
architecture complex and a garden complex of man--made and natural scenery. It has become the symbol of Wuhan for its long history, its magnificent outlook and its imposing architectural style. Guiyuan Temple
Guiyuan Temple, situated on Cuiwei Street, is one of the four biggest temples for Buddhist meditation in Hubei as well as an important
Buddhist temple in China. It was first built in the early Qing dynasty
(1644-1911) by two monks - Baiguang and Zhufeng. Guiyuan
Temple has survived more than 300 hundred years of repeated
cycles of prosperity and decline, and is the leading temple in Wuhan with prosperous public worship, flourishing Buddhist ceremony and many pilgrims. The temple was destroyed and rebuilt many times during the course of its history. Covering an area of 46,900 square meters with a floor space of 20,000 square meters, the temple mainly consists of Daxiongbaodian Hall, Arhat Hall, Sutra Collection Pavilion, etc. Guiyuan Temple is famous not only for spreading Buddhism throughout the whole country, but also for its perfect architecture, excellent sculpture and rich collection of Buddhist
doctrine among the Buddhist temples. In 1956 Guiyuan Temple was listed as a preserved antiques unit of Hubei province and in 1983, it was appointed as one of the key Buddhist temple of Han nationality district in China by the State Council.
East Lake
The East Lake is the pride and joy of the
people of Wuhan.
Millions of residents here get a lot of fun out
of going for a walk along the lakeside in spring, swimming in
summer, appreciating sweet laurel in autumn and admiring plum in
winter.
The lake covers 33 square kilometers and stretches far into the
distance. Ancient pagodas and temples scattered in 34 verdant hills around the lake make the scenic spot more historic and imposing. All the six areas of the East Lake have in common green hills, clear waters, an abundance of woods and typical style of Chu Culture. Perhaps you'll enjoy yourself most in two of them----Tingtao
Pavilion and Moshan Hill.
Willows dance gracefully and water lily sleeps deeply around
Tingtao Pavilion, a three-storey palace building, in front of which the grand and lifelike statue of Qu Yuan is looking up at the sky and sighing sadly at the subjugation of Chu.
On the east side of the lake towers aloft Moshan Hill, where the city of Chu has been set up according to the legend that Zhaolie, King of the Chu State laid an altar and worshiped Heaven there. The
imposing Chutian Tower symbolizes the power and prosperity of the ancient State of Chu.
Among all kinds of flowers, plum, lotus and cassia are of great
reputation. The National Plum and Lotus Research Centre is set up here. The East Lake used to be a private farm several decades ago. In 1950 the farm was turned into a scenic spot. The government provided an enormous financial support to start. In 1982 the East Lake was rated by the State Council as one of the first group of
national key resorts. It receives more than two millions tourists a year.
First Bridge over the Yangtze River
For hundreds of years, it had been a dream to
cross the natural moat of the Yangtze River.
In 1913, Zhan Tianyou, one of China's
well----known railway engineers, visited Wuhan and studied the possibility of the construction of the Yangtze River Bridge. The
bridge was decided to be built between the Tortoise Hill in Hanyang and the Snake Hill in Wuchang. Unfortunately, his dream could not come true. Again, six years later, Dr. Sun Yat-sen put forward a proposal to build a Yangtze River Bridge in Wuhan. Then Nanjing Government invited American experts and made a draft plan. Mao Yisheng, a bridge expert, organized for two designs and the
construction was about to begin. But because of war and lack of money, no one was able to have the bridge built.
After the founding of New China, the central government decided to build the Yangtze River Bridge in Wuhan in 1950. Five years later, news came that the construction would soon begin and it became the focus of world attention. However , more overseas people were half believing and half doubting. Within two years, the Chinese engineers,
technicians and workers, with the help of the Soviet experts,
completed a double----deck bridge for the dual use of automobiles and trains. The wish of "turning a deep chasm into a thoroughfare" was fulfilled.
On October 15, 1957, thousands of people in Wuhan were
overexcited. Cheering sound could be heard on and under the bridge. Trains, automobiles and pedestrians safely crossed the bridge.
More than 30 years have passed. The Wuhan Bridge Bureau of the Railway Ministry has built other ten bridges over the Yangtze River in Nanjing, Chongqing, Zhijiang and Jiujiang. Another highway
bridge 2.5 kilometers down to "the First Bridge" will be finished and put into use at the beginning of 1995.
篇三：英语
《科学》六上复习资料
第一单元：机械和工具
1．在工作时，能使我们省力或方便的装置叫做机械。像螺丝刀、钉锤、剪子这些机械构造很简单，又叫做简单机械。
2．像撬棍这样的简单机械叫做杠杆。杠杆上有三个重要的位置：支撑着杠杆，使杠杆能围绕着转动的位置叫支点；在杠杆上用力的位置叫用力点；杠杆上克服阻力的位置叫阻力点。
3．杠杆省力的秘密：当支点到用力点的距离大于支点到阻力点的距离时省力；当支点到用力点的距离小于支点到阻力点的距离时费力；当支点到用力点的距离等于支点到阻力点的距离时不省力也不费力。
4．省力杠杆：钳子、剪刀、撬棍、开瓶器等；费力杠杆：筷子、镊子、钓鱼竿等。不省力也不费力杠杆：天平、扁担、跷跷板。
5．杆秤由秤杆、秤盘、秤砣、提绳几部分组成。它也是一种杠杆类的工具。
6．指导学生制作杆秤：首先找到秤杆上的三点，定好位置。接着拴好阻力点和支点的细绳，挂好秤盘，系上秤砣。再用挂钩码的方法，在秤杆上画出重量刻度。
7．像水龙头这样，轮子和轴固定在一起，可以转动的机械，叫做轮轴。通过观察，我们发现螺丝刀的刀柄总是比刀杆要粗一些，因此，刀柄是轮，刀杆是轴。
8．轮轴的作用：在轮上用力省力，在轴上用力费力；当轴相同时，轮越大越省力。
9．生活中的轮轴：汽车方向盘、水龙头开关、起子、扳手、门锁把手。
10．固定在一个位置转动而不移动的滑轮叫定滑轮；可以随重物一起移动的滑轮叫动滑轮；把动滑轮和定滑轮组合在一起使用，就构成了滑轮组。
11．定滑轮能改变用力方向，但不省力；动滑轮不能改变用力方向，但能省力；滑轮组既能改变用力方向，又能省力；滑轮组的组数越多越省力；提起重物用几股绳子，就省几分之一的力。
12．生活中的滑轮：①定滑轮：旗杆顶部的轮子、窗帘上的轮子；②动滑轮：工地上提重物的轮子、井口上提水的轮子；③滑轮组：起重机、升降衣架。
13．像搭在汽车车厢上的木板那样的简单机械，叫斜面。
14．斜面的作用：①在斜面上拉重物比直接提起重物省力；②斜面越平缓越省力。
15．生活中的斜面：刀口、楼梯、盘山公路、引桥、螺丝钉、钉子的钉尖。
16．自行车的大齿轮带动小齿轮，转动速度变快，小齿轮带动大齿轮，转动速度变慢。（转速快，用力大；转速慢，用力小。）
17、各种简单机械的比较：
18、写出各类型滑轮的作用。
19、自行车上的各部分应用了哪种简单机械？
第二单元：形状与结构
1．房屋、桥梁结构中有“柱”和“梁”，梁比柱容易弯曲。增加梁的宽度可以增加抗弯曲能力，增加梁的宽度可以增加抗弯曲的能力，增加梁的厚度可以增加大大增加抗弯曲的能力。
2．把薄板形材料弯折成“V”“L”“U”“T”或“工”字等形状，实际上都是减少了材料的宽度而增加了材料的厚度。减少材料宽度虽然降低了一些抗弯曲能力，但增加了厚度，就大大增强了材料的抗弯曲能力。改变材料的形状，可以改变材料的抗弯曲能力。
3．拱形承载重量时，能把压力向下和向外传递给相邻的部分，拱形各部分相互挤压结合得更加紧密。拱形受压会产生一个向外推的力，抵住了这个力，拱就能承载很大的重量。
4．圆顶形可以看成拱形的组合，它有拱形承载压力大的优点，而且不产生向外的推力。
5．球形在各个方向上都可以看成拱形，这使得它比任何形状都要坚固。
6．生活中的拱形：龟壳，贝壳，蛋壳，人的头骨、肋骨、足拱、管状的手臂骨、腿骨，植物的杆、茎、果实，拱门，拱窗，拱桥。
7．用框架结构可以建起很高的建筑而花费的材料却很少，框架结构以三角形为基本构造。
8．三角形框架具有稳定性的特点。利用三角形框架可以加固框架结构。
9．桥面在拱下方的拱桥，桥板可以拉住拱足，抵消拱向外的推力。桥面被水平方向的力拉紧，还增加了桥面的抗弯曲能力。
10．钢缆能能承受巨大的拉力，人们用它们建造的钢索桥，大大增加了桥的跨越能力。
11．钢索桥的结构：由钢缆、桥塔、桥面组成。钢缆是桥承重的主要构件，桥塔是支承钢缆的主要构件，桥塔是支承钢缆的主要构件。从结构上看是吊桥，即桥面被钢缆吊起来。钢索桥的功能：跨度很大。
12．我知道的钢索桥：江阴大桥，夷陵长江大桥，美国跨海峡大桥。
设计桥要考虑：①纸这种材料的特性；②纸的承受力有什么时候特点；③选择形状和结构。④用什么方法增强纸的抗弯曲能力。
13、纸包装箱用的材料叫瓦楞纸。像埃菲尔铁塔这种骨架式的构造叫做框架结构。
14、人的头骨近似于球形，可以很好地保护大脑；拱形的肋骨护卫着胸腔中的内脏；人的足骨构成一个拱形─足弓，它可以更好地承载人体的重量。 15上小下大、上轻下重的物体稳定性好。框架铁塔不容易倒的原因：框架铁塔上小下大、上轻下重，空气阻力小使它不容易倒。
16、拱形抵抗弯曲的能力和抵住拱足的力的大小有关。
第三单元 1、奥斯特在一次实验中，偶尔发现了通电的导线周围有磁场，能使小磁针发生偏转。
2、由线圈和铁芯组成的装置叫电磁铁。电磁铁具有接通电流产生磁性，断开电流磁性消失的基本性质。
3、改变电池正负极接法和改变线圈绕线的方向会改变电磁铁南北极,即改变通过电磁铁中的电流方向会改变电磁铁南北极。
4、电磁铁的磁力是可以改变的。它与线圈圈数、电池数量、铁芯粗细、线圈粗细长短等因素有关。圈数少磁力小，圈数多磁力大；电池少磁力小，电池多，磁力大。电磁铁的磁力大小与使用的电池数量有关：电池少则磁力小，电池多则磁力大。电磁铁的磁力大小与线圈粗细长短、铁芯粗细长短等因素有一定关系。
5、电磁铁和普通磁铁不同的地方：电磁铁通电才有磁性，电磁铁的南北极是可以改变的。
6、玩具小电动机的功能是把电变成了动力。小电动机是由外壳、转子、后盖三部分组成的。
外壳内有一对永久磁铁；转子上有铁芯、线圈和换向器；后盖上有电刷。小电动机中的换向器的作用是接通电流并转换电流的方向。
7、电动机是用电产生动力的机器。它们虽然大小悬殊、构造各异，但工作的原理相同：用电产生磁，利用磁的相互作用转动。
8、用电器有了电就可以进行各种工作─做各种运动或者发光、发声、发热??我们把电具有的这种能量叫电能。
9、能量有电、热、光、声等多种形式。运动的物体也有能量叫动能。能量还储存在食物、燃料和一些化学物质中，叫化学能。任何物体工作都需要能量。
10、所有的用电器都是一个电能的转化器，能够把输入的电能转化成其他形式的能。
11、风、流水、电、汽油都具有能量。风和流水具有动能，电具有电能，汽油具有化学能。电能可以转化成其他形式的能量，其他形式的能量之间也能够转化。
12、电池是把化学能或者光能转化成了电能，生活中电池的种类有：干电池、纽扣电池、光电池和蓄电池。发明了发电机后，人们就能够把其他不同形式的能量大规模地转化为电能了。
13、在我们使用的能量中，煤、石油、天然气是重要的能源。它们所具有的能量是存储了亿万年的太阳能。它们是不可再生的能源。
14、煤的形成过程：是亿万年前的植物遗体在低洼地区大量堆积，逐渐被泥沙掩埋，在长期高温高压作用下，植物慢慢变成了煤。
15、石油、天然气是几亿年前大量的低等生物经过长期、复杂的变化形成的。
16、节约用电，节约用水，节约资源都是节约能源。
17、新能源包括地热能、风能、水能、核能、太阳能和沼气。
第四单元
1、生物多样性指的是地球上生物圈中所有的生物，即动物、植物和微生物，以及它们所拥有的基因和生存环境。生物的多样性包括物种多样性、基因多样性和生态系统多样性。分类是研究生物多样性的基本方法。
2、到目前为止，已发现并分类记载的生物种类超过了200万种，估计地球上现存的物种应有200万到450万种。
3、分区域调查是科学研究常用的方法。不同的环境中生活着不同的生物。
4、我国珍稀的动植物有扬子鳄、藏羚羊、大熊猫、白鳍豚和珙桐。
5、植物的分类方法很多，科学家主要是根据植物的特征对植物进行分类的：可以根据植物茎的质地软硬分为草本植物和木本植物；也可以根据生活环境的不同分为水生植物和陆生植物；根据人类食用的需要可以分为蔬菜、水果、粮食、药材等；根据是否落叶可以分为常绿植物和落叶植物；还可以根据有没有花分成开花植物和不开花植物等等。
6、在植物王国中，已发现的种类有30多万种，开花的植物约占一半以上。不开花植物包括蕨类、苔藓和藻类植物等。
7、分类也是研究动物的一种基本方法，可以根据生存方式的不同分为野生动物和饲养动物；也可以根据运动方式的不同分为水中游的，地上走的和空中飞的；根据它们的身体特征可以分为鸟类、鱼类、哺乳动物、昆虫和软体动物；根据它们的食性可以分为植食动物、肉食动物和杂食动物；还可以根据动物的骨骼特征分成脊椎动物和无脊椎动物。身体中有脊柱的动物叫脊椎动物，没有脊柱的动物叫无脊椎动物。像蚂蚁、蝗虫、蜜蜂那样，身体上有三对足的动物是昆虫类。像金鱼、鲤鱼那样，终生在水中生活，用鳃呼吸的动物是鱼类。身体上长羽毛的动物是鸟类。直接生小动物，并用乳汁喂养小动物的是哺乳动物。
8、根据动物的身体特征，科学家又将脊椎动物分为鱼类、两栖动物、爬行动物、鸟类和哺乳动物，将无脊椎动物分为环节动物、节肢动物等。蚯蚓是环节动物，蜻蜓、蚂蚁等昆虫是节肢动物。
9、在动物王国中，已发现的种类已经有150多万种，是生命世界中类别最多的。而昆虫又是动物王国中种类最多的，已知的昆虫达到100多万种，约占80﹪。菌类不能进行光合作用来制造养料，而靠吸收其他生物或土壤里的营养来生存。生物的形态结构是与它们所生活的环境相适应的。自然选择和人工选择改变着生物，造就了生物的多样性。
10、同一种生物不同个体之间也存在着差异。
11、为什么我们很容易从众多的人中找出某一个人来？因为相同的生物有不同的性状特征，这些特征的不同组合造就了多样的生命个体。
12、动植物具有与环境相适应的一些特殊身体结构。生物的形态结构是与它们所生活的环境相适应的。
13、下列生物的器官有什么特点？它们分别有什么作用？这些生物适宜生活在什么样的环境中？（猫的脚有肉垫，在地上跑时发出的声音较小，不易被捕食对象发现；带钩的鸟爪，容易抓住树干，适宜生活在森林中，并有利于捕抓小动物；鸭的脚有蹼，可以用来划水，适宜生活在水中；苍耳种子上有刺，在陆地上生活容易被动物携带传播种子；莲子有较硬的外壳，可在水中漂流；蒲公英种子上有毛，容易随风漂移，传播种子。）
14、同一种生物生活在不同的地方，身体的形态结构也会有所不同。环境发生变化，生物的形态结构也会发生变化。
15、自然选择和人工选择改变着生物，造就了生物的多样性。保护生物多样性就要保护它们生活的环境。
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