逗号的用法

　　一、逗号+ ing分词短语

　　1、修饰前面的句子，表示伴随或结果。这方面例子比较多，我就不举例了。

　　2、做插入语，位于句中就近修饰名词，是非限定性修饰语。如OG258题的B选项。

　　258. The British sociologist and activist Barbara Wootton once noted as a humorous example of income maldistribution that the elephant that gave rides to children at the Whipsnade Zoo was earning annually exactly what she then earned as director of adult education for London.

　　that the elephant that gave rides to children at the Whipsnade Zoo was earning

　　that the elephant, giving rides to children at the Whipsnade Zoo, had been earning

　　that there was an elephant giving rides to children at the Whipsnade Zoo, and it earned

　　the elephant that gave rides to children at the Whipsnade Zoo and was earning(A)

　　the elephant giving rides to children at the Whipsnade Zoo and that it earned

　　OG 解释说B选项giving rides to children at the Whipsnade Zoo是非限定性修饰，这种情况 下the structure of noted... that the elephant, giving rides ..., had been earning falsely implies that the reader already knows about the elephant--that is, that the existence of this particular elephant is not new information.

　　3、放在一个句子(包括从句)的句末，修饰前面句子的主语。却不是就近修饰句子的宾语。

　　256. The nephew of Pliny the Elder wrote the only eyewitness account of the great eruption of Vesuvius in two letters to the historian Tacitus.

　　The nephew of Pliny the Elder wrote the only eyewitness account of the great eruption of Vesuvius in two letters to the historian Tacitus.

　　To the historian Tacitus, the nephew of Pliny the Elder wrote two letters, being the only eyewitness accounts of the great eruption of Vesuvius.

　　The only eyewitness account is in two letters by the nephew of Pliny the Elder writing to the historian Tacitus an account of the great eruption of Vesuvius.

　　Writing the only eyewitness account, Pliny the Elders nephew accounted for the great eruption of Vesuvius in two letters to the historian Tacitus.

　　In two letters to the historian Tacitus, the nephew of Pliny the Elder wrote the only eyewitness account of the great eruption of Vesuvius.

　　In B, the verb phrase that begins being the only eyewitness accounts modifies the subject of the preceding clause, suggesting nonsensically that the nephew of Pliny the Elder himself was the eyewitness accounts.

　　120. The Parthenon was a church from 1204 until 1456, when Athens was taken by General Mohammed the Conqueror, the Turkish sultan, who established a mosque in the building and used the Acropolis as a fortress.

　　who established a mosque in the building and used the Acropolis as

　　who, establishing a mosque in the building, used the Acropolis like

　　who, when he had established a mosque in the building, used the Acropolis like

　　who had established a mosque in the building, using the Acropolis to be

　　establishing a mosque in the building and using the Acropolis as

　　in E, establishing and using modify Athens, thus producing an absurd statement

　　逗号+ing分词放在句末修饰宾语的例子好像很少，目前我还未见到，如果有谁见到，请指出。我觉得，如果想要用非限定性修饰语修饰宾语最好用定于从句，用逗号+ing分词容易引起歧义。

　　二、n.+分词短语(中间没有逗号)

　　就近修饰名词，做限定性修饰语。如OG237

　　237. It seems likely that a number of astronomical phenomena, such as the formation of planetary nebulas, may be caused by the interaction where two stars orbit each other at close range.

　　may be caused by the interaction where two stars orbit each other

　　may be caused by the interaction between two stars that each orbit the other

　　are because of the interaction between two stars that orbit each other

　　are caused by the interaction of two stars where each is orbiting the other

　　are caused by the interaction of two stars orbiting each other