? It means that the mass of the comet cannot have amounted to as much as one
ten-thousandth of the earth.这表明，这颗彗星的质量甚至不到地球质量的万分之一。 ? It might be thought that carbon dioxide would accumulate in the atmosphere, but
this is not the case.人们可能会认为二氧化碳在大气中会越级越多，但事实并非如此。 ? It remains to be seen if nuclear fusion will be ever become a practical power
source.核聚变是否会成为一种实用的能源，还需拭目以待。（if引导主语从句） ? It remains unknown whether these faults can be corrected.这些缺陷是否可以排除还不清楚。（whether引导主语从句） ? It should be emphasized that the laser is in no sense an energy source.应当强调指出，激光器并不是一个能源。（译为无主句） ? It should be realized that magnetic forces and electric forces are not the same.应该认识到，磁力和电力是不同的 ? It takes time before ozone-depleting chemical can be totally eliminated.要彻底清
除消耗臭氧的化学品还需要时间。 ? It was not until 1948 that the transistor was invented.直到1948年才发明晶体
管。 ? It was not until Madame Curie discovered radium that people have idea of what
radioactivity was.直到居里夫人发现镭以后，人们才开始了解放射性。 ? It, too, was something which was completely at variance with the known laws of
nature.那同样完全不符合当时已知的自然法则。 ? It’s important to learn when the environment is not good for plants and animals,
it is not good for man.懂得当环境不利于动植物时也不利于人类这一点是很重要的。 ? Its being fusible makes metal into liquid when the temperature is high enough.由
于经书是可熔的，所以当温度相当高时，它就会成为液体。
?
K
nowing the electronic instrument of atoms, we can interpret the chemical
properties of the metals in a reasonable way.如果知道了原子的电子结构，我们就可以合理解释金属的化学性能。
? Knowing the strength, it is possible to work backward and determine what factor
of safety was used.由于知道其强度，便可以反过来求出所用的安全系数值。 ? Knowing what might go wrong can help prevent problems from occurring. 了解
哪些地方有可能出问题,有助于防止故障的发生。(what引导宾语从句, what在该从句中作主语)
?
L
aser beams are replacing the mercury arc as a light source.作为一种光源，激
光束正在取代汞弧。
? Lead cannot be drawn out in the form of wire as many of the other metals for its lacking tensile strength.铅之所以不能像许多其他金属那样拉成线状是因为其抗拉强度不够。 ? Leading and trailing edge ribs that are extensively damaged must be replaced.损
伤面积过大的前缘肋和后缘肋，必须更换。 ? Left to its own devices,it run on a cycle of around 25 hours.如果顺其自然，它将
以25小时左右的周期运转。 ? Light travels at the rate of 300,000 kilometers per second. 光以每秒30万千米
的速度传播。 ? Light waves differ in frequency just as sound waves do.同声波一样，光波也有不
同的频率。 ? Like a good pair of sun glasses, the ozone layer acts like a natural filter, blocking
out most of the sun’s harmful UV rays.和优质的太阳镜一样，臭氧层如一张天然的过滤膜，屏蔽了太阳发出的有害紫外线。（增译了acts） ? Like charges repel, but opposite charges attract; that is one of the fundamental laws of electricity.同性电荷相斥，异性电荷详细，这是电学的一个基本定律。 ? Like Jupiter and Saturn, but unlike its near-twin next-door neighbor, Uranus, Neptune appears to have distinct weather patterns.海王星和它的近似孪生的隔壁邻居天王星不一样，却像木星和土星，似乎有独特的气象模式。 ? Liquids, except for liquid metal such as mercury, are not considered to be good
conductors of heat.除了液体金属和水银外，其他液体则被认为是不良导热体。 ? Little information is given as to the origin of life.关于生命起源方面的资料极少。 ? Loss of control is most likely to occur on inductive loads.失控现象在电感负载
时最可能发生。 ? Lubricate each movable part before it wears away.要对每个运动部件进行润滑，
以免磨损。
?
M
achine parts of irregular shape can be washed very clean by ultrasonic
waves.超声波能把形状不规则的机件冲洗的干干净净。
? Manufacturing processes may be classified as unit production with small
quantities being made and mass production with large numbers of identical parts
being produced.制造过程可分为单件生产和大量生产。前者指的是生产少量的零件，后者则是指生产大量相同的零件。
? Many elements in nature are found to be mixtures of different isotopes.人们发
现，自然界里的许多元素，都是各种不同的同位素的混合物。 ? Many health-conscious women increase their risk rejecting red meat, which
contains the most easily absorbed form of iron.许多保健意识太强的女性会由于他们拒绝食用牛肉或羊肉而增加其（缺铁的）风险，因为这些肉中所含的铁质最易被吸收。 ? Many industrial coding systems are neither total monocodes nor polycodes, but
are hybrids.很多工业用的编码系统既非单码，也非多码，而是单码与多码的混合。 ? Massage can help loosen contracted, shortened muscles and can stimulate weak,
flaccid muscles.推拿有助于将收缩和绷紧的肌肉放松，并且还能刺激较弱的不结实的肌肉组织。（过去分词作前置定语） ? Materials are of two types, metallic or nonmetallic.材料有金属和非金属两类。 ? Matter is transported in a circulatory system.循环系统输送物质。
? Mercury is also a metal, although it is the liquid state.汞也是金属，尽管它是液态的。 ? Metallic surfaces should be greased and decrease friction.金属表面必须涂上润
滑脂，以减少摩擦。 ? Methods of cutting should be employed which are unlikely to generate an undue
amount of heat.应采用不易产生过多热量的切割方法。 ? Miniature gas detector is chiefly featured by small size, light weight, complete
functions and long continuous working time.袖珍式瓦斯检测器的主要特点是体积小、重量轻、功能全、连续工作时间长。 ? Modern aircraft are so heavy that the wings must develop a very large lift force in
order to sustain the aircraft.现代飞机如此之重,以致要支撑住飞机, 机翼必须产生极大的升力。(that引导结果状语从句) ? More metal is removed when the feed is increased.进给量增加时，切除的金属更
多。（转译为定语） ? Morphologically and anatomically the leaf is the most variable plant organ.在形态学上和解剖学上，叶是变化最大的植物器官。 ? Most colds and flus are caused by viruses, and yet antibiotics don’t harm viruses
at all.大多数感冒和流感是由病毒引起的，而抗生素对杀灭病毒丝毫不起作用。 ? Moving out from a source in uniform medium,a wave travels in straight lines.当
波从均匀介质中的波源移出时，呈直线传播。
? Much of people’s physiology is timed by an internal pacemaker.人们的生理在
很大程度上是由体内的整律气安排时间的。 ? Much of the gas separates when the oil reaches the surface but does so
underground.大部分石油气是在石油到达地表面时分离的，但也有在地下分离的。 ? Much research is currently being carried out, too, to find composite bearing
materials with low wear rates a well as small frictional coefficients.目前还在进行大量研究，以找到具有低磨损率，同时又具有低摩擦系数的复合轴承材料。
?
N
ever take antibiotics unless a doctor tells you to.如果不是医生让你使用抗
生素,千万不要擅自使用.
? No case has ever been found in which conservation of energy doesn’t hold.尚未发现能量守恒定律不适用的情况。 ? No sooner were the pieces of charcoal rubbed against the glass rod than
electricity appeared on the rod.木炭屑同玻璃棒一摩擦，玻璃棒就带电。 ? Nobody knows what proportion of aircraft accidents occur during the pilot’s
natural night time.还没有人知道有多大比例的飞机失事发生在飞行员的自然夜间。 ? Noises may develop in a worn engine.磨损了的引擎里可能会产生各种噪声。 ? Not all signals of interest have finite energy.并非所有我们关心的信号都有有限
的能量。 ? Not every substance exists in three states.并非每一种物质都有三种状态。 ? Not everybody is convinced the Leaning Tower of Pisa really can be saved.并非
每一个人都相信比萨斜塔真的能够免于坍塌。 ? Not only was it possible for a magnet to move round a current-carrying wire but
also for a current-carrying wire to move around a magnet.不仅磁铁能绕载流导体运动，载流导体也可绕着磁铁运动。 ? Now that they have electronic computers, mathematicians are solving problems
they would not have dared tackle a few years ago.由于有了电子计算机,数学家们现在正在解决几年之前还不敢着手解决的问题。(now that引导原因状语从句) ? Nowadays, more and more plastic products are used in place of metal.现在，越来
越多的塑料制品被用来替代金属。
? Nowhere else in the world have geologists found fossils of this creature, or of closely related creature.地质学家在世界上其他地方还未找到这种动物的化石，甚至其亲近动物的化石也未曾找到过。（并列连词or转译为“甚至”，
表示递进）
?
O
f the two possibilities , this is more likely than that.两个可能性中，后者比
前者更有可能。
? Oil and gas will continue to be our chief source of fuel.石油和天然气将继续是
燃料的主要来源 ? Once it is combined, nitrogen is not chemically inert any longer.氮气一经化合，
在化学上它就变得活泼。 ? Once the cold water enters the flack, the vapor pressure falls quickly.一旦冷水进
入长颈瓶，蒸汽气压就迅速下降。 ? Once the levels reached 6 percent the crew members would become mentally
confused, unable to take measures to preserve their lives.一旦含量达到6%，（飞船上的）人员就会神经错乱，无法采取保护自己生命的措施。 ? One material can be distinguished from another by their physical properties.根据
物理性质，可以把一种材料与另一种材料区分开来。 ? One of every 200 babies born has chromosome abnormalities.每200个已出生的
婴儿中有一个染色体异常。 ? One wonders also why Nature with some snakes concocted poison of much
extreme potency.人们也不明白，为什么大自然在某些蛇身上配置如此剧烈的毒液。（动词wonder具有否定含义） ? One wonders also why Nature with some snakes concocted poison of much extreme potency.人们也不明白，为什么大自然在某些蛇身上配置如此剧烈的毒液。（动词wonder具有否定含义） ? Open the key and an induced current in the opposite direction will be obtained.如果把电键断开，就会得到反相的感应电流。 ? Orchard without precaution will suffer heavy loss in case cold wave occurs.如果
寒潮来袭，不采取预防措施的果园将会遭受严重损失。 ? Ordinary movements would be impossible but for friction.如果没有摩擦力，常
见的活动就不可能进行。 ? Ordinary movements would be impossible without friction available.如果没有摩
擦力，常见的活动就不可能进行。（译为条件状语从句） ? Other isolation methods are being developed.目前正在研究其他隔离方法。 ? Our bodies need carbohydrates to make sugar which is used to produce energy.人体需要碳水化合物来制造以产生能量的糖。