Whatever we think of technology, it is here to stay and it is a natural and almost invisible part of children's lives. (educationbusinessuk.net)
Twenty years on and electricity was such a pervasive but largely invisible part of the infrastructure that companies no longer needed someone to watch over it. (newscientist.com)
Use a gentle cleaning solution which is suitable for upholstery if necessary, testing this on a usually invisible part of the cover before use. (outandoutoriginal.com)