标志结构二：句子以同位语开始，主语一致

　　错误句式：An orphan raised in humble surroundings, the novel Great Expectations has a hero who is given a fortune and sets out to become a gentleman.

　　改为： An orphan raised in humble surroundings, the hero of the novel Great Expectations later is given a fortune and sets out to become a gentleman.

　　原则是句首的同位语描述的对象orphan 应与句子主干的主语保持一致。

　　例如Khan 语法‘War and Poetry: T.S. Eliot's Fourth Quartet’第5 题

　　A valued public intellectual figure, Eliot's skills as a writer, editor, and lecturer were in high demand.

　　A.NO CHANGE

　　B.Eliot's writing, editing, and lecturing skills were in high demand.

　　C.Eliot was in high demand as a writer, editor, and lecturer.

　　D.high demand was placed on Eliot's skills as a writer, editor, and lecturer.

　　做题思路：

　　1. 识别考点：主语前面有主语的同位语A valued public intellectual figure

　　2. 这个同位语表示的是人，所以主语也应该是一个人，C选项主语是 Eliot，所以正确。

　　标志结构三：介词+doing, 主语一致

　　错误句式：By using a thimble to protect your finger from the needle, the thimble makes sewing easier.

　　改为：By using a thimble to protect your finger from the needle, you can sew more easily.

　　由此看出，句子中若出现了介词加doing，那么句子主干的主语应与doing 的执行者保持一致。

　　例如Khan 语法‘The Ambassadors: A Meditation on Mortality’第3 题

　　Upon viewing the painting from the front, the confident ambassadors are seen by the careful observer standing amongst symbols of prosperity, above the hazy and abstract anamorphic image.

　　A.NO CHANGE

　　B.Symbols of prosperity are seen by the careful observer amongst the confident ambassadors,

　　C.amongst the confident ambassadors, symbols of prosperity are seen by the careful observer,

　　D.the careful observer sees the confident ambassadors standing amongst symbols of prosperity,

　　做题思路：

　　1. 识别考点：句首有状语Upon viewing the painting from the front

　　2. 句子主语应该与这个状语中viewing 这个词的逻辑主语一致，只有D 选项的主语the careful observer 符合。

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