设有泵体密封环，而叶轮密封环为可选用件。

Sealing ring is fitted on pump body, while impeller sealing ring is an optional part.

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年前，我刚刚开始山地自行车运动的时候，我更愿意选用零件尽可能少尽可能简单的自行车。

When I started mountain biking 10 years ago, I went for the simplest possible bike with the fewest possible components.

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本文介绍了NJD433型柴油机主要零件选用和试验的情况。

This paper presents the material selection and the experimental results of the main parts for NJD433 diesel engine.

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