If any part of a shell command is enclosed by back quotes (a character also known as a grave accent), it is executed and the output placed on the command line.

如果shell脚本的某一部分用单引号(也称为重单符)括起来，那么将执行这个部分并将结果放在该命令行内。

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The only written accent is the grave, which is used when-ever a word of more than one syllable stresses the final vowel (città—city).

唯一的标音符号是“、”，这个符号在两个音节以上的词的重音落在最后的元音上时使用（città；

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It has often been described by biographers as high-pitched with a Kentucky accent, and this was difficult to reconcile with the grave baritone we associate with the man reading the Gettysburg Address.

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