whAt ADvAntAgE DiD thE 20th CEntury hAvE ovEr thE 19th CEntury
A．thE nEw invEntion oF thE trAin mADE trAvEling possiBlE.
B．inFormAtion CoulD BE sprEAD immEDiAtEly.
C．pEoplE DiDn’t gEt As muCh ExErCisE AnymorE.
D．trAvElling By BoAt wAs still DAngErous.