Because you need both a voltage source and a ground in order to create a complete circuit, you need to have a sourcing input or output connected to a sinking output or input.

因为在一个完整的电路中必须有一对电源和地。

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The sinking digital output controls the line by using a transistor to leave the line high (at + v) or to ground the line to 0 v.

Sinking数字输出通过三极管来控制连接线上的电平为高电平(+ V)或是低电平(0 V)。

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Since the 20th century, when Wells began to draw water from the ground to support local industry, Venice has been sinking.

从20世纪自地底抽取井水以支持当地工业开始，威尼斯就开始下沉。

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The resort to this sinking moral high ground is made by people properly concerned with the human ill of racism, but so preemptively concerned with it that they now layer that racial consciousness over the evidence of other features of reality.

CENTERFORSECURITYPOLICY: A Campaign of Willful Blindness on Terrorism

Moreover, environmental regulations and inevitable lawsuits from groups opposing refineries popping up in their backyard mean oil companies risk sinking billions into breaking ground, only to never see a facility get up and running.

FORBES: Magazine Article