Free indirect discourse is constructed by the substitution of those subjects, and the rules of substitution coincide with general grammar.

自由间接引语即由潜在的多个主体之间的代换而构成，而且代换规则与一般语法规则一致。

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The reactivities and selectivities of aliphatic and aromatic free-radical(substitution)reactions were explained semi-quantitatively by the perturbation molecular orbital theory.

从而用微扰分子轨道理论半定量地解释了脂肪族的游离基取代和芳香族的游离基取代反应的反应性和选择性。

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Due to the consideration of environmental protection, the substitution of lead-containing solder with lead-free solder has become an inevitable trend in the 21st century.

进入21世纪，由于环境保护的要求，锡铅焊料将逐步被无铅焊料所取代。

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With the game stretched and there to be won by either team, City boss Sven-Goran Eriksson made a defensive-looking substitution, withdrawing the fading Geovanni in his free role for Kelvin Etuhu to make a five-man midfield.

BBC: Paul Scharner celebrates his second goal of the season

Seconds after the substitution, Lee Sharpe sent in a beautifully weighted free-kick which was headed in with precision by Wetherall in the 71st minute.

BBC: Bantams down Magpies