A(13)1.Attention must be paid to the working temperature of the machine.应当注意机器的工作温度。

2.An understanding of essential character of scientific investigation is best acquired from the study of a representative particular science.要了解科学研究最本质的特点，最好是对特定的典型学科进行研究。

3.As we know, all matters consist of molecules, and molecules of atoms.众所周知，一切物质由分子组成，而分子由原子组成。

4.All of this proves that we must have a profound study of properties of proteins.所有这一切证明，我们必须深入地研究蛋白质特性。

5.A new kind of computer –small, cheap, fine—is attracting increasing attention.一种新型的计算机越来越引起人们的注意——这种计算机体积小巧，价格低廉，性能优越。

6.A computer system consists of a computer and some peripherals.计算机系统是由计算机和一些外部设备构成的。

7.Adverse to iron，mercury is in a liquid state at ordinary temperature.水银与铁不同，在常温下是液态。

8.AC can be changed into DC with great ease.交流电可以极其容易地被转变成直流电。

9.Animals, although they need some inorganic food, cannot live on it alone.尽管动物需要无机物的营养，但是却不能单独以此维持生命。

10.Another important factor to be taken into consideration is that current strength is equal at certain point in a series circuit.需要考虑在内的另一个重要因素是电流强度同串联电路中某些点的强度相同。

11.A minimum electric power system is shown in Fig.1，a combination of an energy source, a prime mover, a generator, and a load.最小的电力系统如图1所示，它由能源、原动机、发电机和负载构成。

12.Apart from the international agencies controlled by the U.N., many scientific and technological organizations, both governmental and privately owned, are pooling their resources and incorporating themselves into supra-national bodies; a good example is the Organization for Economic Cooperation and Development, with over 20 member-countries throughout the world.除去联合国直属的国际机构之外，许多科技组织不论是政府的还是私营的，都在将它们的资源汇集起来并将自己合并成超国家的组织。

由世界上20多个国家参加的经济合作与发展组织就是一个范例。

13.Aluminum remained unknown until the nineteenth century, because nowhere in nature is it found free, owing to its always being combined with other elements, most commonly with oxygen, for which it has strong affinity.铝总是和其他元素结合在一起，最普遍的是和氧结合在一起，因为铝对氧有很强的亲和力。

由于这个原因，在自然界中任何地方都找不到游离状态的铝；所以一直到十九世纪人们才知道有铝。

B(4)14.But for friction, the driving wheel would not run the belt, neither would the belt run the wheel to be driven.要是没有摩擦力，主动轮就不能带动皮带，皮带也就不能带动被动轮。

15.Being cooled in the air, this kind of steel becomes harder and harder.在空气中冷却之后，这种钢就变得越来越硬。

16.Both of the substances are not soluble in water.这两种物质都不溶于水。

17.Being large or small all magnets behave the same.所有磁铁，无论大小，其性质都一样。

C(3)18.Cool slowly to minimize cracking. 要慢慢冷却，以最大限度的减少开裂。

puting machines are essentially machines for recording numbers, operating with numbers, and giving the result in numerical form.计算机本质上是一种记录数字、运算数字并给出数字结果的机器。

20.Copper has less resistance than aluminum for the same size wire, but aluminum, being much lighter in weight, has less resistance per unit of weight.对于同样粗细的电线来说，铜比铝的电阻小，但由于铝的重量很轻，所以它单位重量的电阻较小。

D(5)21.Depending upon certain conditions, there may or may not be free electrons in semiconductors.半导体是否存在着自由电子，这取决于某些条件。

22.Don`t let the stresses inside the material exceed the elastic limit, or else permanent deformation will result.不要使材料的应力超过弹性极限，否则会产生永久变形。

23.Ductility of a metal is usually much less when hot than when cold.热状态的金属韧性一般要比冷状态的金属低得多。

24.Design is a series of operations involved in taking a product from a conceptual stage to a form that meets both company goals and customer expectations.设计是一系列的操作，包含该产品从构思阶段到同时满足公司目标和客户期望的结构样式。

25.Dimensioning is a complicated work and long experiences are required for the mastering of it. 进行尺寸标注是一项复杂的工作，需要长期经验才能完成。

E(2)26.Even the dissolution in water cannot enable common salt to change its chemical properties. 即使我们将普通食盐溶于水，也不能改变其化学性质。

27.Earthquakes seem less easy to be controlled by man than weather.人类要控制地震似乎比控制天气更难。

F(3)28.Fig 1 incorporates many of the factors which must be considered in developing a satisfactory system.图1所示的许多因素，在研制性能良好的系统时必须予以考虑。

29.Faraday discovered the Law of Electromagnetic Induction after years of trial，error，and trial again.经过几年的试验、失败、再实验，法拉第终于发现了电磁感应定律。

30.For reasons the alternating current is more widely used than the direct current.由于种种原因，交流电比直流电用得更加广泛。

G(6)31.Gases differ from solids in that the former have greater compressibility than the later.气体和固体的区别在于前者比后者有更大的压缩性。

32.Gasoline is appreciably volatile. 汽油具有很强的挥发性。

33.Gold is similar in color to brass. 金子的颜色和黄铜相似。

34.Going through the process of heat treatment, metals become much stronger and more durable. 金属经过热处理后，强度更大，更加耐用。

35.Given the weight and the specific gravity of a body, we can calculate its volume. 已知物体的重量和比重，就可求出其体积。