在《容易犯錯(cuò)的形容詞從句》一文里，知道形容詞從句總是跟在被修飾的名詞(即先行詞)后面。例如：

① Any change which causes the formation of new matters is a chemical change.(在主句主語(yǔ)的名詞之后)

② Plastics is an important material which is widely used in industry.(在主句補(bǔ)足語(yǔ)名詞之后)

③ It has certain features that are easily recognised.(在主句賓語(yǔ)名詞之后)

在下列情況下，形容詞從句和所修飾的名詞隔開(kāi)：

㈠被介詞短語(yǔ)隔開(kāi)，如：

④ Magnets work through lines of force that extend between the two ends of the magnet.

⑤ A molecule may be defined as the smallest particle of matter that can exist without changing its nature.

④里的形容詞從句和先行詞“l(fā)ines”被介詞短語(yǔ)“of force” 分離。⑤里的卻被另一個(gè)介詞短語(yǔ)“of matter”隔開(kāi)。

㈡被分詞短語(yǔ)隔開(kāi)，如：

⑥ There is no method known to medical science today that can effectively cure cancer.

⑥里的形容詞從句和先行詞“method”之間被過(guò)去分詞短語(yǔ)“ known to medical science today”隔開(kāi)。

上述兩種隔離情況可以理解，也被接受。

另外還有一種分隔情況，也偶爾見(jiàn)到，特別在科技英語(yǔ)中，但這種離異法，值得商榷。

例如：

⑦ Several other ideas came along that enabled engineers to design still smaller units.

⑧ Ninety-six substances are known which chemists consider to be elements.

⑦和⑧里的形容詞從句和先行詞“ideas”及“substances”之間都被主句的謂語(yǔ)動(dòng)詞“came along”和“are known”分開(kāi)。

這類(lèi)的分隔情況，多在主句謂語(yǔ)動(dòng)詞是被動(dòng)語(yǔ)態(tài)(the passive voice)時(shí)才出現(xiàn)，如例⑧，但謂語(yǔ)動(dòng)詞是主動(dòng)語(yǔ)態(tài)(the active voice)的話，也可以，如例⑦，只是數(shù)量少些。

為什么要把形容詞從句常見(jiàn)的位置和先行詞分開(kāi)呢?主要原因是：先行詞所在的主句較短，而修飾先行詞的形容詞從句則很長(zhǎng)。為了平衡主句和從句，才采用這方法。雖然如此，但它和一般的形容詞從句的位置有很多抵觸，恐怕引起混亂。

為了減少不必要的麻煩，最好改用別的句式。其中一個(gè)方法是將形容詞從句改為另外一個(gè)獨(dú)立的簡(jiǎn)單句(如例⑨&╆);另一個(gè)辦法是采用并列句(如例⑩&╇)：

⑨ Several other ideas came along. Such ideas /They enabled engineers to design still small units.

⑩ Several other ideas came along and these ideas enabled engineers to design still small units.

╆ Ninety-six substances are known. Chemists consider them to be elements.

╇ Ninety-six substances are known and chemists consider them to be elements.