A catalyst changes the speed of chemical reaction without entering into it.

催化剂能改变化学反应的速度而不参加反应。

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A layer of chemical film can be formed on the surface of solid through chemical reaction. The quality of film is decided by the speed of chemical reaction of film surface.

通过化学反应可以在某些固体表面上形成一层化学薄膜，膜的质量是由成膜时膜表面的化学反应速率决定的。

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And, in a specific stage, due to the speed of chemical reaction is not stable, resulting in the gain of the process, the inertia time and the pure lag will occur the corresponding change.

并且，就某一个具体的阶段而言，由于化学反应的速度不稳定，导致过程的增益、惯性时间和纯滞后也会发生相应的变化。

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