21．Inability to build high-voltage generators1 and motors gives to the transformer immediate2recognition 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，这就立即便大家认识到变压器是发电与配电之 间灵活性非常高的中间环节。
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 tourismwhether by winter or by summer．
宜人的气候、变化不大的温度、稀有的雨量、灿烂的阳光与明媚的天空，所有这所有使 突尼斯成为冬夏理想的旅游胜地。
23．We explain the differences between gases and liquids bysaying that the molecules3 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块，大家以此来讲解气体和液体之间有什么区别。
24．For about the last 200 years，the structural4 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、数学家和工程师们进步了结构理论，其目的在于通过计算给结构物的设计工作提供靠谱的基础。
25．By the quiet persistence5 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 beenpressed farther back．
因为真理探索者顶着保守派偏见的逆流，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大家更远的地方。
26．When a man picks up a weight from the floor and raises it above his head，he has in effectinserted 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，事实上他是把我们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。
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，由于印度面积大，譬如，从德里到马德拉斯的距离，就比伦敦到罗马还 要远。
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 enoughfoods to preserve much of the earth's population from stavation．
甚至目前，地球上的很多自然财富正遭到破坏，很多珍贵动植物已面临灭绝之灾，为使地球上大部分人口免于饥饿而生产出足够的粮食也愈加困难了。
29．If the Earth，Moon and Sun move into a direct line，with the Moon in the middle，the dark body of the Moon blots6 out the briliant disk of the Sun，and we witness a solar eslipse．
倘若地球、月球和太阳运行到一条直线上，月球在中间，那样月球的暗体就遮住了太阳的亮盘，于是大家便看到日食。
30．As natural science treats of the mutual7 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 phenomena8 of nature．
自于自然科学研究的是各种物质的相互转化、变化和进步，因而大家深入研究自然科学以便控制各种自然现象，这具备重大意义。
31．With irrigation came surplus food，which meant that large numbers of people were freed trom the land to pursue nonagrarian specialitiestechnological development，scholarship for itssakeand war。
伴随有了灌溉，粮食就有了剩余，这就意味着大量人就可解脱出来从事农业以外的工作一进步工艺，研究其学问甚至参加战争。
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-
开普勒第一发现了每一个行星都以椭圆曲线绕太阳运行，太阳则坐落于椭圆的焦点。
33．It should be noted9 that a rocket does not depend on the atmosphere for its propulsion，but would actually perform better in the absence of an atmosphere becauseOf lessened10 air resistance．
需要注意，火箭的推力与大方无关，在没大方的状况下，因为空气阻力减小，火箭事实上会运行得更好。
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．
电力一直以高电压低电流的方法进行远距离输送的，又是以交流电的形式送电的，由于这种交流电易于升压或降压。
35．When one considers the immense change in the size and reliability11 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．
当大家考虑到计算机和其他所有电子器件在尺寸和靠谱性方面所发生的很大变化时，就不难了解，依据感觉进行这种活动控制的计算机必然会出现。
