People put it in the oven all day in a heavy pot on a low heat.

人们一整天都把它放在炉上的一个很重的锅里，用小火加热。

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Melt the butter over a medium-low heat. When it is melted and bubbly, put in the flour.

用中低火把黄油加热。待黄油熔化起泡后，放入面粉。

《柯林斯英汉双解大词典》

As it remained clear for longer than usual it also bled more heat into the Arctic atmosphere. This caused higher air pressures, reducing the gradient between the Iceland low and the Azores high.

当它在比以前更长的时间里保持不结冰的状态，它也会将更多的热量输入北极区的大气层，这就使北极区的气压变高，使冰岛低压和亚速尔高压之间的梯度变小。

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If you do make your own broth, Ms. Bloomfield recommends simmering it over low heat for two to three hours, so the result is clear and deeply flavored.

WSJ: April Bloomfield's Hearty Root Vegetable Soup | Slow Food Fast

If it reaches a temperature that is too low, it automatically turns the heat up again, eliminating the need for a human to wait for it to reach boiling point and monitor whether it stays there.

CNN: Sensor keeps cooking on the boil

After the mass of onions in the pan has significantly reduced in volume the onions are softer and suppler and have fallen considerably it's time to turn the heat to medium-low and ride this baby out for as long as it takes, stirring and turning the onions every 10 minutes or so and making sure that they don't start to stick or burn at any point.

WSJ: Momofuku Recipes by David Chang