减压阀有直动型和先导型两种。

Valves are direct acting and pilot-type two kinds.

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上行先导与下行先导连接，于是产生了一次回击，随后又是五次以上的直窜先导型回击。

This upward leader connects with the downward leader and a return stroke occurs. Five more dart leader-return strokes follow.

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到目前为止，中心已成功地孵化企业20多家，其中有些企业已成为当地的科技先导型企业。

So far, it has succeeded in incubating over 20 enterprises, some of which have become pioneering technological enterprises in local places.

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