发布时间:2025-02-06 01:48:43
铁钉要求不高,可以用235材料,也可以用195材料,一般生产厂家都是用卷板边丝拉成丝再用制钉机生产.这样成本会降你不少.
我有一口水井潜水泵以放下60米深但抽水只能抽20分钟是正常岀水20分钟后水量就不急了这是什么原
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