(1) Once the flower has been pollinated and fertilized, the plant provides the newly formed seeds with food materials, which will be needed when they themselves germinate.
译文：花一旦授了粉并受了精，植株就会对新生种子提供养料贮藏，以备种子未来萌芽之需。
(2) Once the overall program strategy has been clearly established, then the syntactic details of the language can be considered. Such an approach is often referred to as "top-down" programming.
译文：一旦清楚地制定了全面的编程策略，然后便考虑该语言的句法细节。这种方法经常称作“自顶向下”的程序设计法。
(3) This equilibrium is completely destroyed when the virgin soil is brought into cultivation.
译文：未垦土壤一经种植，这种平衡就完全遭到破坏。
(4) Several approaches to the problem of ladle skull slag or deoxidation-scum removed was being tried.
译文：罐内结壳，熔渣或脱氧浮渣清除问题的几项解决方案正在实验中。
另外，在被动句中，by 短语有时表达方式、方法或手段，而不只表达行为的发出者(doer)。如::
(1) The temperature of the liquid is raised by the application of heat.
译文：加热可以提高液体温度。
(2) Useful facts may be collected either by making careful observation or by setting up experiment.
译文：通过仔细的观察或做实验可以收集到有用的数据。
最后，以“it”为形式主语的被动语态句型是科 技英语中的一种典型句型。翻译时应加以注意。如:It is said / reported / to be discussed that……分别译为“据说……，据报道……，……有待讨论”。
2.5 长句子的翻译
在科技文体中经常使用长句子，使用长句子可以做到表述的严谨性和逻辑性。这主要是因为在阐述科学事实、科学现象等事物的内在联系和解释一些科技术语或名词时，需要大量使用各种从句( 尤其是定语从句) 和大量的介词短语、形容词短语、分词短语或副词等作后置定语，以及分词短语表示伴随情况等而造成的，造成了翻译的难点。要想做到翻译准确，就必须仔细研读原文，分析句子结构，弄清各成分之间的关系，从整体上理解原文。如：
(1)The central notion here is that it will one day be possible to construct a "universal assembler" which can be programmed to build，quite literally, anything that is composed of atoms and consistent with the rules of chemical stability.
其中心思想就是：将来某一天可能会造出一种“万能装配手”，它能按程序构建由原子组成并且符合化学稳定原则的任何东西。这个句子很长，但其实是个简单句，主干是个主系表结构，“The central notion here is that...”。“that”引导一个表语从句。表语从句中，“it”是形式主语，真正的主语是“to construct a 'universal assembler' which can be programmed to build，quite literally，anything that is composed of atoms and consistent with the rules of chemical stability”。其中，“which”引导定语从句，修饰“a 'universal assembler'”，而which 引导的定语从句中又包含一个that 引导的定语从句，修饰anything。
(2)With the advent of the space shuttle, it will be possible to put an orbiting solar power plant in stationary orbit 24, 000 miles from the earth that would collect solar energy almost continuously and convert this energy either directly to electricity via photovoltaic cells or indirectly with flat plate or focused collectors that would boil a carrying medium to produce steam that would drive a turbine that then in turn would generate electricity.