There are three significant scientific concepts, kinetic chain length and number average degree of polymerization and radical life, in the chapter of the radical chain polymerization.

其中动力学链长、平均聚合度、自由基寿命是三个重要的学术概念。

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They are worst off in the North West, where the average length of a healthy life is only 64.4 years, and overall life expectancy is 73.4 years.

BBC: Northerners suffer more ill health