四、排序分叙
The
structure design itself includes two different tasks，the design of the
structure, in which the sizes and locations of the main members are
settled，and the analysis of this structure by mathematical or graphical
methods or both，to work out how the loads pass through the structure
with the particular members chosen.
“结构设计本身包含两项不同任务：ー是结构设计，确定主要构件的尺寸和位置；二是用数学方法或图解方法，或兼用这两种方法进行结构分析，以便在构件选定的条件下计算出各荷载通过结构情况。”
这里增添了“ 一是……”，“二是……”以便醒目。
Mechanical
supply ventilation may be of the central type consisting of a central
fan system with distributing ducts serving a large space or a number of
spaces, or of the unitary type with little or no duct work, serving a
single space or a portion of a large space.
“机械通风可分成两类；ー类是集中式的，一类是单元式的。集中式通风是由集中风机及若干管道组成的通风系统，供一个大房间或若干个小房间使用。单元式通风只用极少的管道，甚至不用管道，供一个单个房间或ー个大房间中的一局部空间使用。”
五、颠倒增益
With
organic farming there is an enormous potential for dealing with a large
portion of America's environmental problems by recognizing that organic
materials are actually a resource rather than "wastes"
“有机物质实际上是ー种资源，巧不是废物，基于这种认识，所以采用有机耕作方式对于处理美国大部分的环境保护问题是具有巨大的潜力的。”
把后面叙述的事物提到了句子的最前面，次序上予以颠倒，又将by recognizing予以深化，译为“基于这种认识”，对原文加以增益。
The
great difficulty of introducing radically new computer architectures
which requires customers to rewrite most of their software excluded the
possibitity for these techniques to find their way to the commercial
market place.
采用全新的电子计算机体系结构，势必要求用户改写其大部分软件，由于存在这个困难，这种技术在商品市场上寻找出路的可能性就被排除了。
六、成份移位
Altering
the shape of hollow chamber on the side of the rotor where combustion
takes place -- normally a simple paddle shape but capable of hundreds of
different variations without too much difficulty -- will make
stratification even more effecient.
在转子的那ー边有一空心室，燃烧在此进行，此室通常呈简单的浆叶状，但能较易地变换上千种形状，改变此燃烧室的形状，能使分层进气更为有效。
将句子中间成份往外移，改变原句子两头小中间大的现象，使译句结构匀称，意义清晰。
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