请先看看⼏个例⼦：
Mary is pretty; so is her sister.(Mary 很漂亮，她妹妹也⼀样。)
Mary speaks French; so does her sister.(Mary 说法⽂，她妹妹也⼀样。)
Mary is pretty; she is also smart.(Mary 很漂亮，她还很聪明。)
第 1 句当中以副词 so 替代前⾯的形容词 pretty 以避免重复。第 2 句当中以助动词 does 替代动词 speak 以避免重复。第 3 句则是以代词 she 替代名词 Mary 以避免重复。像 so, do, she 这些⽤来取代他⼈以避免重复的字，可以笼统称为 代词（pro-forms）。各种代词当中，写作时⽐较容易出错、因⽽也⽐较值得探讨的，就是 代词（pronouns）。
代词是⽤来代替名词⽚语以避免重复的⼀种词类。例如：
The dog ate the bone.(狗吃了⻣头。)
He liked it.(觉得很好吃。)
句 2 中的 he 与 it 就是代词，分别代替句 1 中的名词⽚语 the dog 与 the bone 以避免重复。 the dog 与 the bone 称为 先⾏词（antecedents）。
代词算是⽐较简单的⼀种词类，不过在写作时还是经常出现代名词的错误，所以接下来我们整理出⼀些代名词使⽤时最常出现错误的地⽅，提醒读者注意。
People often think that our difficulties are unique.⼤家经常以为我们碰到的困难是独⼀⽆⼆的。
句中的代词 our，代表的先⾏词是 people。但是，people 是第三⼈称、our 却是第⼀⼈称，并不⼀致。下⾯两种改法都符合⼀致性的要求，可以接受：
People often think that their difficulties are unique.
We often think that our difficulties are unique.
If the campaign succeeds in raising huge sums, the sponsors will devote it all to disaster relief.如果宣传运动成功募得巨款，主办单位将全数⽤于救灾。
代词 it 是单数，它代替的先⾏词 huge sums 却是复数，不⼀致。下⾯两种改法都可以：
If the campaign succeeds in raising huge sums, the sponsors will devote them all to disaster relief.
If the campaign succeeds in raising a huge sum, the sponsors will devote it all to disaster relief.
When a teacher takes his students on a field trip, he is fully responsible and must bring every one of them safely back to school with him.⽼师带学⽣做户外旅⾏时要负全责，必须把每⼀名学⽣安全带回学校。
这⾥⾯有⼀个写作时会碰到的问题。如果先⾏词是某⼈、性别不清楚，从前的做法是⼀律视为男性、代词使⽤ he 这 ⼀类。但是⾃从⼥权运动兴起、⼀些⼥权运动先驱率先解构语⾔⽂字，就不再适合把上述的情况⼀律视为男性，⽽应该⽤ he or she 这个⽐较男⼥平等的⽚语做代名词。不过，he or she 这种⽤法有时会显得很笨重。像上⾯那句话，尊重⼥权的话可能要这样讲才⾏：
When a teacher takes his or her students on a field trip, he or she is fully responsible and must bring every one of them safely back to school with him or her.
这种说法仍然不佳，因为实在太啰嗦了。如果碰到这种情况，最好的办法是⼲脆⼀律视为⼥性，可以平衡⼀下：
When a teacher takes her students on a field trip, she is fully responsible and must bring every one of them safely back to school with her.
Although the new regulations allow them to do it, high school graduates seldom go abroad for higher education.虽然新规定允许这样做，但是⾼中毕业⽣还是很少出国深造。
代词 it 必须有⼀个先⾏词，⽽且这个先⾏词应该是名词⽚语。但是整句话中找不到 it 的先⾏词是什么。从意思上判断的话似乎代表的是 go abroad for higher education，但那是以动词 go 为主的「述部」、并⾮名词⽚语，所以不宜使⽤代名词 it 来替代。应该改写如下：
Although the new regulations allow them to do so, high school graduates seldom go abroad for higher education.
改成 do so，没有了代词、变成助动词 do 加上副词 so，「这样做」，代表的就是后⾯ go abroad for higher education 这个部分。
代词只能有⼀个合理的先⾏词。如果⼀个代名词有两个以上的先⾏词、⽽且都说得通，那么这个句⼦就没有把话讲清楚、是不好的句⼦。例如：
When tourists first arrived in this new resort, the locals thought they were very lucky people.观光客初抵这个新渡假区时，当地⼈认为他们是⾮常幸运的⼈。
这个句⼦不好，因为没把话讲清楚。代词 they 有两个可能的先⾏词：tourists 与 the locals。这种情况就会造成模棱两可。如果 they 的先⾏词是 tourists，这个句⼦的意思是「当地⼈认为这些观光客是幸运⼉」——可能是羡慕这些观光客有钱有闲。反之，如果 they 的先⾏词是 the locals，这个句⼦就得解读为「当地⼈认为⾃⼰是幸运⼉」——可能是想到可以发⼀笔观光财了。两种说法都讲得通，表示这个句⼦并没有把话讲清楚。代名词如果有两个可能的先⾏词，就会造成这样的结果，⽽这⼜是写作时经常犯的⽑病，要特别注意。
上⾯这个句⼦应该避免使⽤代词，不然⽆法避免模棱两可的缺点。两种意思可以分别修改如下：
When tourists first arrived in this new resort, the locals thought these outsiders were very lucky people.
When tourists first arrived in this new resort, the locals considered themselves very lucky people.