同位格是指什么?同位格的作用?

同位格片语 (Appositive Phrase)
同位格片语系它前面紧邻的一个字的补充、说明和铺陈。我们通常使用另一种片语来做为同位格片语。
• My favorite teacher, a fine chess player in her own right, has won several state-level tournaments. [名词片语当同位格片语]
• The best exercise, walking briskly, is also the least expensive. [动名词片语当同位格片语]
• Tashonda's goal in life, to become an occupational therapist, is within her grasp this year, at last. [不定词片语当同位格片语]

使用同位格来结合句子

同位格可能是结合句子最有效的工具。同位格或同位格片语是句子中先前出现的人事物的另一名称。你可以将同位格视为省略掉关系代名词和连缀动词的修饰子句。同位格通常是 (但并非都是) 插入语句，它的前后都要加逗点来与句子的其他部分分开。

Sacagawea, who was one of the Indian wives of Charbonneau, who was a French fur-trader, accompanied the expedition as a translator.
A pregnant, fifteen-year-old Indian woman, Sacagawea, one of the wives of the French fur-trader Charbonneau, accompanied the expedition as a translator.

注意：在上面第二个句子中，Sacagawea 的名字是插入语句 (在结构上，句子已指出她是一名十五岁的印地安孕妇)，因此需要一对逗点来分开；然而，Charbonneau 的名字对句子的意思至关重要 (否则谁知道