代名词和其代理的先行词要在人称 ,单数或复数,和性别上一致.一些常见的代词是: he, his ( 阳性单数 ); she, her ( 阴性单数 ); it, its ( 单数 ); they, their, these, those ( 复数 ); that, this ( 单数 ). 比如下面的例句中 , compounds 和 their 一致 , protein 和 it 一 致 .
Many related compounds were synthesized and their antivirus activities were studied.
Growth hormone is a protein. It promotes human body growth.
下面的例句中,the 应该用 their 取代 .
The potential antioxidant capacity of compound A and compound B could be deduced from the protective effects against oxidative stresses.
宜改为 : The potential antioxidant capacity of compound A and compound B could be deduced from their protective effects against oxidative stresses.
用代名词时 除了要保持一致外,还要避免代理不清的情况出现,以免不清楚它们到底指什么而引起误解．
The crude sample was dissolved in water and extracted with organic solvent. It was then evaporated
to yield the product.
It 指 organic layer 还是指 water layer? 不明确，最好不用 it.
宜改为： The crude sample was dissolved in water and extracted with organic solvent. The organic layer was then evaporated to yield the product.
During meal hormones are released after which blood flow increases in the stomach.
Which 既可以代表 meal 也可以代表 hormones, 容易产生误解 .
宜改为： During meal hormones are released. After their release stomach blood flow increases.