whAt is thE mAin iDEA oF thE pAssAgE
A．thE worlD is shrinking physiCAlly.
B．thE 20th CEntury sAw inCrEDiBlE invEntions..
C．thE wAy wE livE AnD CommuniCAtE hAs ChAngED ovEr thE CEnturiEs.
D．thE ComputEr rEvolution hAs mADE liFE morE ConvEniEnt.