指代不清主要讲的是代词与被指代的人或物关系不清，或者先后所用的代词不一致。 Mary was friendly to my sister because she wanted her to be her bridesmaid.
(玛丽和我姐姐很要好，因为她要她做她的伴娘。)
读完上面这一句话，读者无法明确地判断两位姑娘中谁将结婚，谁将当伴娘。如果我们把易于引起误解的代词的所指对象加以明确，意思就一目了然了。这个句子可改为：
Mary was friendly to my sister because she wanted my sister to be her bridesmaid.
And we can also know the society by serving it yourself.
剖析：句中人称代词we 和反身代词yourself指代不一致。
改为：We can also know society by serving it ourselves.
七． 不间断句子(Run-on Sentences)
什么叫run-on sentence? 请看下面的例句。
病句: There are many ways we get to know the outside world.
剖析：这个句子包含了两层完整的意思：“There are many ways.” 以及“We get to know the outside world.”。简单地把它们连在一起就不妥当了。
改为：There are many ways for us to learn about the outside world. 或：
There are many ways through which we can become acquainted with the outside world
八． 措词毛病(Troubles in Diction)
Diction 是指在特定的句子中如何适当地选用词语的问题，囿于教学时间紧迫，教师平时在这方面花的时间往往极其有限，影响了学生在写作中没有养成良好的推敲，斟酌的习惯。他们往往随心所欲，拿来就用。所以作文中用词不当的错误比比皆是。
病句：The increasing use of chemical obstacles in agriculture also makes pollution.(农业方面化学物质使用的不断增加也造成了污染。)
剖析：显然，考生把obstacles“障碍”，“障碍物”误作substance“物质”了。另外“the increasing use (不断增加的使用)” 应改为“abusive use (滥用)”。
改为：The abusive use of chemical substances in agriculture also causes/leads to pollution.