For even greater efficiency consider buying a tankless water heater. Tankless water heaters only heat water when it is needed, instead of keeping a reserve of water at a constant temperature.

购买无水箱热水器（电热水器）是更加节能的做法，电热水器只在需要的时候对水进行加热，而不会对保存在水箱内的水加热保温。

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Slow efficiency at threshold is observed to be nearly constant over the wide range.

在广域范围内观测到的低效阈值近似为常数。

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USES frequency conversion control system, can real time monitoring gas supply lines gas pressure, make the gas supply pipe gas pressure constant, improve the production efficiency and product quality.

采用变频控制系统后，可以实时监测供气管路中气体的压力，使供气管路中的气体的压力保持恒定，提高生产效率和产品质量；

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The struggle to improve efficiency and cut costs is a constant irritant in labor- management relations.

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Not only did he fail to carry his weight, he was a constant and serious drain on the Army's efficiency.

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