Stuck at 'Pulling the required container. This may take several minutes if you're doing this for the first time. Please wait here'

I am new to TAO. When I issused my first tao command, a messasge promted ‘Pulling the required container. This may take several minutes if you’re doing this for the first time. Please wait here’. However, I have not seen any progress for more than half an hour and it seems my program just stuck at the step.


Anyone has the same issue? I cannot find any clues on Google.