以it 做形式主語，而把真正的主語放到后面，這是英語特有的一種句型，也是科技英語中常見的一種句型。這種句型的譯法既是千姿百態(tài)的同時又是有規(guī)律可循的。概括地說，有下列幾種譯法：

譯成漢語不定人稱句

In the United States the customary voltage for household use has become 110-120 V since it was discovered that higher voltages could cause fatal accidents.美國通常的家用電壓是110-120伏，因?yàn)槿藗儼l(fā)現(xiàn)，更高的電壓會造成致命的事故。

We have already observed that for a long time it was incorrectly believed that current flowed from positive to negative.我們已經(jīng)觀察到，人們過去長期錯誤地認(rèn)為電流是由正極流向負(fù)極的。

譯成無人稱句

It is obvious that resistance is responsible for heating and lighting effects of many common household appliances.很明顯，許多家庭常用電器設(shè)備的加熱和照明作用都依靠電阻。

It may be safely said that many other materials besides amber could be charged by rubbing.可以有把握地說，除了琥珀意外，許多其他物質(zhì)通過摩擦也能帶電。

把that從句、動詞不定式等譯成真實(shí)主語

It is important to realize the two points about forging and pressing.弄清鍛壓的這兩個要點(diǎn)是重要的。

It is quite remarkable that so much of this rapid development of electrical devices and the resulting industry took place during the nineteenth century, when the nature of electricity was not completely understood.電力裝置以及由此而興起的工業(yè)的這一迅速發(fā)展主要發(fā)生在19世紀(jì)，而當(dāng)時人們對電的性質(zhì)還不完全了解，這是十分值得注意的。

主表倒譯

即將作真正主語的從句或動詞不定式譯成表語，原表語譯成主語。

It is desirable to use large units for measurement of large quantities and small units for small quantities.最好是用大的單位來測量大的量值，用小的單位來測量小的量值。

It is a matter of common experience that it is much easier to roll bodies along than to slide them.通常的經(jīng)驗(yàn)是物體想前滾動比向前滑動容易得多。

It is noteworthy that small as atoms are, they contain vast amounts of energy.值得注意的是原子隨小，卻具有很大的能量。

把形式主語it和它的謂語譯成一個短語，把從句譯成句子的主干

It goes without saying that these waves travel at the speed of light.顯然，這些波是以光速傳播的。

It follows that radar is an electronic system for locating aircraft or cloud patterns.由此可見，雷達(dá)是用來測定飛機(jī)位置或云型位置的電子系統(tǒng)。