Can the data be acquired from all the channels when there is only one signal input channel?

The A/D board has high input impedance. The value of the input impedance can be 10M-1G . At the same time, there is no resistance between the channel and the ground. So the signal input value can not be zero. To solve the problem, we can connect the vacant channels to the ground or put a 1K-1M resistance between the vacant channels and the ground . It certainly will not affect the signal input channel. So if it is not necessary to show the data from the vacant channels, users do not need to care about them.