21.Inability to build high-voltage generators and motors gives to the transformer immediate recognition as a highly flexible link between the generation and distribution of electrical energy.
制造高压发电机和高压电动机是不可能的，这就立即使人们认识到变压器是发电与配电之间灵活性很高的中间环节。 (本句是简单句。主语是inability，谓语是gives，宾语是recognition.不定式短语to build.……motors作定语，修饰inability.give recognition to.……as.……，“承认……是……”。介词短语between—。energy作定语，修饰link.)
22.The mildness of its climate，with slight temperature variations and infrequent rainfall，combined with a high average level of sunshine and brilliant shies，a11 make it idea for tourism whether by winter or by summer.
宜人的气候、变化不大的温度、稀少的雨量、灿烂的阳光以及明媚的天空，所有这一切使突尼斯成为冬夏理想的旅游胜地。(with.……和combined with把三个主语连接起来。all是总括词，总括上述的三个主语。idea是it宾语补足语。it代替上文中Tunisia突尼斯。 bywinter.……这里by作“当……时候”解。例：They don't work by day but by night.他们日间不工作，夜间工作。whether.。or，“不论是……还是”，用作连词，连接两个并列成分。)
23.We explain the differences between gases and liquids bysaying that the molecules in a liquid are not moving about so fredy as the molecules in a gas and are very much closer together.
液体分子不像气体分子那样能自由地到处运动，而是比较紧密地聚集在一起，我们以此来解释气体和液体之间的区别。(介词短语by saying.……作方式方法状语，说明谓语explain.)
24.For about the last 200 years，the structural theory has been devdoped by scientists，mathematicians and engineers，with the very practical object of providing a reliable basis for the design of structures by calculation.
大约近200年来，科学家、数学家和工程师们发展了结构理论，其目的在于通过计算给结构物的设计工作提供可靠的基础。 (with.……obiect.……for.……是介词复合结构，起目的状语作用。)
25.By the quiet persistence of the truth-seekers， working upstream against the flow of ancient prejudice，mankind has entered into new realm of health，and the borderlines of death have been pressed farther back.
由于真理探索者顶着守旧派偏见的逆流，默默无闻、坚持不懈地努力工作，人类才得以进 入了新的健康王国，而死亡的界线则被抛到离我们更远的地方。(介词短语By.……truth-seekers用作原因状语，说明谓语动词hasentered.)
26.When a man picks up a weight from the floor and raises it above his head， he has in effect inserted his body between the weight and the earth and pushed the weight one way with his hands，and thee arth the other way with his feet.
当一个人从地板上拿起重物并把它举到头顶上时，实际上他是把自己的身体置于重物与地面之间，他用双手朝着一个方向推着重物，而用双脚朝着另一方向推着地面。(pick up，“拿起”。in effect，“实际上”。one way，“朝着一个方向”。the other way，“朝着另一方向”。这两个短语前均省略介词in，作状语。and与the earth之间省略了谓语pushed.)
27.But this is not possible because of the size of the country，with the distance from Dehli to Madras，for example，being greater than that from London to Rome.
但这是不可能的，因为印度面积大，譬如，从德里到马德拉斯的距离，就比伦敦到罗马还要远。(with，名词+分词的结构，可用作状语和定语。句中with the distance.……being用作定语，对size进行补充说明。that from.……that代替distance.)
28.Even at this moment many Of the earth's natural treasures are being destroyed，manyvaluable animals and plants are been killed off，it is becoming increasingly difficult to grow enough foods to preserve much of the earth's population from stavation.
甚至现在，地球上的许多自然财富正遭到破坏，许多珍稀动植物已面临灭绝之灾，为使地球上大多数人口免于饥饿而生产出足够的粮食也越来越困难了。(to preserve.……from，“使……免于”。)
29.If the Earth，Moon and Sun move into a direct line，with the Moon in the middle，the dark body of the Moon blots out the briliant disk of the Sun，and we witness a solar eslipse.
假如地球、月球和太阳运行到一条直线上，月球在中间，那么月球的暗体就遮住了太阳的亮盘，于是我们便看到日食。(with the Moon in the middle是with引出的介词复合结构，在句中起补充说明作用。)
30.As natural science treats of the mutual transformation，changes and development of various kinds of matter，it is of great tmportance for us to make a profound study of it so that we may control the phenomena of nature.
自于自然科学研究的是各种物质的相互转化、变化和发展，因而我们深入研究自然科学以便控制各种自然现象，这具有重大意义。(treat of.。，“论述”。带逻辑主体for us的不定式短浯to make.……nature作主语，it是形式主语。so that引导目的状语从句。be of.。，“具有”。)
31.With irrigation came surplus food，which meant that large numbers of people were freed trom the land to pursue nonagrarian specialities—technological development，scholarship for its sake——and war.
随着有了灌溉，粮食就有了剩余，这就意味着大批人就可解脱出来从事农业以外的工作一发展工艺，研究其学问——甚至参加战争。 (with.……“随着”，引导的短语作状语。
With the approach of sunset it became chilly，come surplus food是倒装语序，food是主语，came是谓语。which引导特种定语从句，指上句话。不定式to pursue.……war有结果状语的意味。)
32.First of all， Kepler found that each planet goes around the sun in a curve called an ellipse，with the sun at a focus of the ellipse. -
开普勒首先发现了每个行星都以椭圆曲线绕太阳运行，太阳则位于椭圆的焦点。(with the sun at，……为介词复合结构作状语，补充说明。)
33.It should be noted that a rocket does not depend on the atmosphere for its propulsion，but would actually perform better in the absence of an atmosphere becauseOf lessened air resistance.
应该注意，火箭的推力与大气无关，在没有大气的情况下，由于空气阻力减小，火箭实际上会运行得更好。(in the absence of anatmosphere含有虚拟条件的意味。)
34.Electrical power is always carried over long distances as a high-tension current at low-currentstrength.It is also sent as an alternating current，for such current is comparatively easily transformed eitherup ordown in voltage.
电力总是以高电压低电流的方式进行远距离输送的，又是以交流电的形式送电的，因为这种交流电易于升压或降压。(两个as构成的介词短语都用作方式方法状语，分别说明iscarried和issent.)
35.When one considers the immense change in the size and reliability of computers and all other electronic devices that has taken place，it is clean that computers for doing this type of control of movement according to sense impression will certainly be available.
当我们考虑到计算机和其他所有电子器件在尺寸和可靠性方面所发生的极大变化时，就不难明白，根据感觉进行这类活动控制的计算机一定会出现。 (for.……movement是computers的定语，介词短语according to sense impression作状语，说明动名词doing.)
36.In l664 the great English diarist，John Evelyn，published，with the approval of the Royal Society of London，a book Sylva or a Discourse of Forest Trees in which one sees，perhaps for the first time，a realization that trees，then so important in the construction of ships，were indeed becoming sadly depleted and that something urgently needed to be done by way of deliberate planting to ensure enough for the future.
1664.年，英国伟大的日记作家J.Evelyn，经伦敦皇家学会批准出版了一部森林志，即《林木论》。在这本著作中，人们可以说是第一次了解到一个现实：当时，在造船业中如此重要的树木的确正在悲惨地遭到浩劫;必须采取紧急措施，通过认真植树以便确保未来有足够的树木。(with.…… London介词短语作条件状语修饰published，其宾语是a book.在which定语从句中，one泛指人们。a realization是谓语sees的宾语。so important in……ship是非限定性定语，用来修饰trees.句中两个that均引导同位语从句用来揭示realization的概念内涵。)
37.As a magnetic material becomes more and more magnetized，more and more of its magnetic domains line up，with their north poles a11 pointing inone direction and their south poles in the opposite direction.
随着材料的磁性变强，材料中越来越多的磁畴便会排列起来，其N极均指向一个方向， 而S极则指向相反的方向。 (介词复合结构with.一用来对主句中的谓语lineup进行补充说明。)
38.Since the earth is slightly flattened at its poles，the distance of its surface at the north pole or south pole from its center is less than that at the equator.
由于地球的两极略为扁平，所以南北两极地表面离地心的距离比赤道地表面离地心的距离要近一些。(distancefrom.。，“离……的距离”。that代替distance.)
39.Solar energy seems to offer more hope than any other source of energy，particularly since those areas most in need of water lie rather close to the equator and have a relatively clear atmosphere.
太阳能似乎比任何其他能源更有希望，尤其是因为这些迫切需要水的地区离赤道很近，那里有较清洁的大气。(lie和have是两个谓语，主语是those areas.most in need of water为介词短语作定语修饰areas.)
40.For a very long time man has been seeking the possibility of combining various metals into alloys with a view to obtaining better materials for given purposes.
长期以来，人们一直在寻找把各种金属熔成合金的可能性，其目的在于为某些用途获得更好的材料。(with.viewto.。，“以……为目的”，“为……起见”，是短语介词，引出的介词短语起目的状语作用。)
41.It means reorganising them on democratic lines，with governing boards made up of workers and technicians from the trade unions concerned，loyal to the concept of nationalisation as a force for social changes and operating their industry according to anational plan arrived at democratically by the community as a whole.
这意味着：要以民主的方式，由有关工会的工人和技术员所组成的管理董事会来改组各项工业。这些工人和技术员作为社会改革的一支力量要忠实于国有化这一观念，同时他们必须按照由作为整体的社会用民主方法制定的全国性计划来管理各工业。(on.……1ines，“按照……方针，办法”，作状语。 with.……concerned介词短语作状语，用来修饰动名词reorganising.Made up of.……过去分词短语作定语修饰boards.loyal.……changes为形容词短语修饰workers and technicians.as force for social changes是“工人和技术员”的同位语，operating.……as a whole为现
在分词短语作定语，也是用来修饰workers and technidans.它是与形容词短语loyal……。是并列关系。arrive at作出(决定)，得出(结论)等。句中arrived at.……whole是过去分词短语作定语修饰plan.)
42.Thirty-five seconds into the flight，with the solid rockets pumping out maximum power，Challenger—like all its predecessors—was undergoing severe aerodynamic stress.
“挑战者”号在其固体燃料助推火箭发出最大推力的推动下，飞行了35秒后，同以前的航天飞机一样，正在承受着巨大的空气动力的压力。(with the solid.……复合结构用作状语，有条件意味。)
43.A gas，such as steam (water vapor) in the cylinder of asteam engine，has neither deftnite shape nor definite volume-it changes its sshape and also its svolume with change in the shape and volume of the container.
气体，例如蒸汽机汽缸中的水蒸气，既无一定的形状，也无一定的体积。气体的形状和体积是随着容器的形状和体积的改变而变化的。(change.……with，“随……而变化”。)
44.Their wide use in industry is due not only to these properties but to the fact that the common metals can be shaped into required objects by deformation and by casting into mold，and to the fact that their properties can be greatly altered by alloying with other metals.
金属在工业中之所以得到广泛的应用，不仅是由于它们具有上述这些性能，而且还由于普通的金属可以通过加工和铸造而形成所需要的制品，同时还由于金属的特性可通过与其他金属熔成合金而显著地改变。(due to，“由于”。to these properties，to the fact，and to the fact都是due所要求的。句中两个that均引出同位语从句。)
45.Newton generalized the idea by supposing that any two particles in the universe gravitate towards each other with a force varying inversely as the square of the distance between them and directly as the product of their masses.
宇宙中任意两个质点均以某种力在相互吸引，该力与两质点之间距离的平方成反比，而与它们质量的乘积成正比，牛顿就是通过这一假设概括了这种思想。 (with a force varying.……为介词复合结构，用作状语，说明gravitate.vary directly as……，“与……成正比”。vary inverse1yas，“与……成反比”。)
（责任编辑:doublejp）
