Doctors, firefighters and some other professionals frequently work 24 - hour shifts and may have to work several shifts in a row. (newscientist.com)
Over the past 6 million years our diet must have undergone several shifts, when we started using stone tools, learned to cook with fire, and settled down as farmers. (newscientist.com)
Within the development of these school - wide policies, several shifts need to happen. (edutopia.org)