单项选择题
A.food irradiation should be carried out with careB.it is more urgent to irradiate foodsC.medical researches into treatment of the diseased should be strengthenedD.Americans are beginning to accept food irradiation
A.Making School Buses Even Safer for ChildrenB.Seat Belts Needed on School BusesC.Alternate Safety Devices and ProceduresD.Safety in and around School Buses
A.construction methods are saferB.buildings are made from a set of standardized unitsC.similar buildings can be producedD.all units are produced on the site