英语习惯上常常以引导词it作形式主语，而把真正作主语的动名词、不定式或主语从句放在谓语之后。此时，it本身无词义，汉译时无需译出。这种句型是英语中特有的ー种句型，也是科技英语中常见的ー种句型。这种句型的译法多种多祥，概括一下有下列几种译法：

1. 顺译法

这种译法就是基本按照原文句子的语序，将含有it作形式主语的英语句子译为汉语的无主句。如：

* It is likely that the endosperm of many other plants through a similar free-cell, liquid stage.

可能许多其他植物的胚乳也经历了相似的游离細胞和流体胚乳阶段。

* It should be noted that such layers with a lower velocity could be detected.

应该注意到，这类低速层是可以探测到的。

* With the more complex shapes, it is necessary to go through a series of stages before the final shape can be produced from the raw material.

对于较复杂的形状，必须经过几个步骤才能把原料加工成最后的形状。

2. 倒译法

所谓的倒译法，就是将位于句尾的真正的主语（包括主语从句、不定式短语、动名词）先译，并在译文中作主语。如：

* 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。

* It is possible to improve the antichatter characteristics of a machine tool by incorporating extra damping.

采用外部减震来改善机床的抗震性能是可行的。

* It is important to realize the two points about forging and pressing.

弄清锻压的这两个要点是重要的。