90. Pollution and waste combine to be a problem everyone can help to solve by cutting out un-nessary buying，excess consumption and careless disposal of the products we use in our daily lives.
这些污染物和废物结合在一起就会造成一大问题。每个人可以帮助解决这一问题：不去购买不必要的东西、削减过量的消费、不要粗枝大叶地处置日常生活中所使用的物品。(这是一个主从复合句。主句Pollution.……problem.everyone.……daily lives是省略that的定语从句，修饰 problem，that在定语从句中作宾语时，可以省略。句中Pollution和waste是主语，谓语是combine，不定式短语to be aproblem为结果状语。we.……use.……1ives也是省略that的定语从句，修饰products.)
91.Chemicals are made from the elements which have been put together in different forms to make wood or glass or rugs or water，or even the bones，blood，and muscles of ourbodies.
化合物是由那些不同形式组合在一起而构成了木头、玻璃、毯子、水或者甚至我们身体的骨骼、血液和肌肉的元素组成的。(不定式短语to make.……是结果状语，说明谓语have been put.)
92.We notice that every day the sun appears to travel across the sky from east to west，but many people have not noticed that the stars also move across the sky in the same direction.
我们注意到，太阳每天看来是从东到西越过天空，但是很多人没有留意到星星也是沿着同样的方向越过天空的。(不定式短语to travel.……是系词appears的表语。)
93.The invention of the thermometer，the barometer，and the hydromter in the sixteenth and seventeenth centuries extended man's capability to observe，and sharpened his desire to interpret and to understand.
在16世纪和17世纪发明了温度计、气压计和比重计，这就扩大了人的观察能力，并加强了人们解释和认知(自然界)的愿望。 (to observe修饰capability.to interpret and to understand修饰desire.)
94.Intelligent beings which are just beginning to develop on remote worlds may be ready to pick up our signals in thousands of years'time，or when life on earth has become extinct.
在遥远的星球上现在刚开始进化的有智慧的生物，也许要在千万年以后，即在地球上生物绝迹后，才能收到我们发出的信号。(ready是形容词，不定式短语to pick up.……作其状语。)
95.When the effect of inductance is such as to cause an induced voltage in the salne circuit in which the changing current is flowing，the term self-induction is applied to the phenomenon.
当电感效应在变化的电流流过的同一电路里足以引起感应电压时，我们就用“自感”这个词来描述这一现象。(such as引导的不定式短语to cause.……表示结果。)
96.It was not until the 19th century，when magnetism was shown to be the product of electricity，that serious research into the nature of permanent magnetism began.
直到19世纪证明了磁是电产生的那个时候，人们才开始对永久磁性的本质作认真的研究。(to be the product.……为主语补足语，说明magnetism.)
97.A rocket is independent of air because it contains an explosive mixture which consists both of a fuel to beburned and a supply of oxygen.
火箭飞行依赖空气，因为它本身装有爆炸混合物，这种混合物是由待燃烧的燃料和氧气组成的。(to be burned在句中作定语修饰fuel，有“将来”的含义。)
98.The first law of motion explains what is to be understood by force： it iS that which tends to change the state of rest of aboby，or of uniform motion in astraight line.
第一运动定律阐明了对力应该怎样理解：力就是改变物体的静止状态或匀速直线运动状态的作用。(“be+不定式”有情态动词的意思，即“可能”，“应该”，“必须”。)
99.In almost every cause the electric current that an ammeter measures must actually pass through theinstrument，so thismetermust beconnected inserieswith the circuit inwhich it is to measure the current.
几乎在所有的情况下，安培计所测量的电流实际上必然要通过该电表，因此安培计必须与待测电流的电路串联在一起。(句中“be十不定式”有表示“将要”的意思。)
（责任编辑:doublejp）
