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按阀杆的螺纹位置划分,可分为明杆闸阀和暗杆闸阀两种。
Position by the valve stem threads are divided into clear and dark bar bar gate valve two...
youdao
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按阀杆的螺纹位置划分,可分为明杆闸阀和暗杆闸阀两种。
Position by the valve stem threads are divided into clear and dark bar bar gate valve two...
youdao