One way of explaining this is that pins configured as INPUT make extremely small demands on the circuit that they are sampling, say equivalent to a series resistor of 100 Megohms in front of the pin.

• 我们可以这样来理解，在取样时，只需要在电路中通过非常小的电量，就好比在该接口前放置了100欧姆的电阻。