When parents have joint physical custody, both parents have frequent and substantial contact with their child, but the child does not necessarily split time equally between the parents. (info.legalzoom.com)
For good and loving parents, the children should have substantial contact with both parents; the clinical research supports this idea. (illinoisdivorcelawyerblog.com)
Either answer suggests that the rock has been in substantial contact with water, for instance allowing minerals to dissolve, and explaining the salty ice grains we see coming out of the surface.» (newscientist.com)