3. 指代错误与冠词错误
同单复数一样，解指代错误题也要关注指代的对象到底是单数还是复数：
(1)During the 1980s' culture wars, school systems across the country pulled some books from library shelves because its content was deemed by parents and teachers to be inappropriate.（07年1月新六级改错第9题）这里its指代前面的some books，所以物主代词应该是their而不是its。
(2)As a result, children memorize processes such as mathematical formulas or the periodic table, only to forget it shortly afterwards.（07年1月六级改错第7题）容易发现it指代前面的processes，因为是复数，所以该用复数的宾格them。
(3) At same time（06年6月六级改错第七题）地球人都知道的at the same time是固定短语。
(4) in first paragraph（06年1月六级改错第一题）序数词前面要加the，这是初中的知识。
(5) a number of leprosy cases around the world has been cut by ninety percent during the past ten years.(05年1月六级改错第一题)表示数量多少应该用the number of。
(6)The fast-growing population's demand for food，they warned，would soon exceed their supply…(04年1月六级改错第二题)这里的their指代population，而人口是一个单数的概念，所以物主代词要用its。