e rate ③at which the change is effected.
这是一个以主句开头的复合句。其中包含三个从句: ①以by virtue of which引导的定语从句； ②以which引导的修饰resistance的定语从句； ③以at which引导的修饰rate的定语从句。
3) 并列成分多或长的长复合句
正确判断并列成分是能否对长句进行正确分析的重要因素。这些并列的成分，既可以是并列的分句，也可以是并列的主语、谓语、宾语、定语和状语等。而且，并列成分一般多由and等连词连接。在大多数情况下，根据该连词后面那个词或短语的性质到前面去找与之性质相同的词或短语，即可对并列成分做出正确判断。例如:
Such activities as investigating the strength and uses of materials, extending the findings of pure mathematics to improve the sampling procedures used in agriculture or social sciences, and developing the potentialities of atomic energy, are all examples of the work of the applied scientist.
该句中and后面是动名词短语developing the potentialities of atomic energy, and前面也有两个动名词短语investigating...和extending...，可以肯定这三个动名词短语并列，用作as引导的定语从句的主语。
4) 从句中含有从句的长复合句
在有的长句中，某个从句本身有可能也是含有一个或一个以上从句的复合句；甚至这种从句本身又含有从句。遇到这种比较复杂的现象，必须要对每个从句的性质做出正确的分析，找出与它发生关系的词。例如:
A further inference was drawn by Pascal, who reasoned that if this "sea of air" existed, its pressure at the bottom (i.e. sea-level) would be greater than its pressure further up, and that therefore the height of mercury column would decrease in proportion to the height above the sea-level.
此句中，who引导的定语从句为一复合句，含有一个以 that引导的宾语从句。而这个that 引导的宾语从句又是一个复合句，其中含有一个以if引导的条件状语从句，and连接的两个并列的宾语从句。
为了能够做好长句结构的分析，掌握好专业英语中关于复合句、非谓语动词的知识是非常必要的。在接下来的几课中，将介绍一下关于复合句、非谓语动词的知识。然后我们再结合实例来介绍长句结构分析的方法（见Lesson 17，物理学专业英语中的长句分析（二）) .
9.2 专业英语阅读9.2.1 Thermal Equilibrium and Temperature（热平衡及温度） Temperature is familiar to us as the measure of the hotness or coldness of objects or of our surroundings.
Our sense of touch can usually tell us if an object is hot or cold. Early in childhood we learn that to make a cold object warmer, we place it in contact wit
h a hot object and to make a hot object cooler, we place it in contact with a cold object.
When an object is heated or cooled, some of its phys