During periods of low demand, jockey pumps are used to meet these lowerwater flow requirements.
在需求较低的时期,赛马泵用于满足这些较低的水流量要求。
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A keel also provides weight low under the water to lower the boat's center of gravity below the waterline, which is needed so that the boat bobs back upright if knocked over by wind or waves.
In the same condition, the lower the salinity of stratum-water and the stronger the additional conductivity influence, the easier the make of low resistance oil layer.