in thE pAst, mAn DiDn’t hAvE to think ABout thE protECtion oF his EnvironmEnt. thErE wErE FEw pEoplE on thE EArth, AnD nAturAl rEsourCEs sEEmED to BE {{u}} (56) {{/u}} . toDAy things ArE {{u}} (57) {{/u}} . thE worlD hAs BEComE too {{u}} (58) {{/u}} . wE ArE using up our nAturAl rEsourCEs too quiCkly, AnD At thE sAmE timE wE ArE {{u}} (59) {{/u}} our EnvironmEnt with DAngErous ChEmiCAls. iF wE {{u}} (60) {{/u}} to Do this, humAn liFE on thE EArth will not survivE. EvEryonE {{u}} (61) {{/u}} toADy thAt iF too mAny Fish ArE tAkEn From thE sEA, thErE will soon BE nonE lEFt. yEt, with moDEm Fishing {{u}} (62) {{/u}} morE AnD morE Fish ArE CAught. wE know thAt iF too mAny trEEs ArE Cut Down, {{u}} (63) {{/u}} will DisAppEAr AnD nothing will grow on thE lAnD、yEt, wE {{u}} (64) {{/u}} to usE BiggEr AnD morE powErFul mAChinEs to {{u}} (65) {{/u}} morE AnD morE trEEs. wE rEAlizE thAt iF rivErs ArE pollutED with wAstE proDuCts From FACtoriEs, wE will DiE. {{u}} (66) {{/u}} , in most CountriEs wAstEs ArE {{u}} (67) {{/u}} put into rivErs or into thE sEA, AnD thErE ArE {{u}} (68) {{/u}} lAws to stop this. wE know, too, thAt iF thE {{u}} (69) {{/u}} oF thE worlD ContinuEs to risE At thE prEsEnt rAtE, in A FEw yEArs, thErE will not BE Enough {{u}} (70) {{/u}} whAt CAn wE Do to solvE thEsE proBlEms iF wE EAt morE vEgEtABlEs AnD lEss {{u}} (71) {{/u}} , thErE will BE morE FooD AvAilABlE For AnyonE. lAnD thAt is usED to grow Crops {{u}} (72) {{/u}} FivE timEs morE pEoplE thAn lAnD whErE AnimAls ArE kEpt. our nAturAl rEsourCEs will {{u}} (73) {{/u}} longEr iF wE lEArn to rECyClE thEm. thE worlD populAtion will not risE so quiCkly iF pEoplE usE moDEm mEthoDs oF Birth {{u}} (74) {{/u}} . FinAlly, FF wE EDuCAtE pEoplE to think ABout thE proBlEms, wE shAll hAvE A BEttEr AnD ClEAnEr {{u}} (75) {{/u}} in thE FuturE.

A．nAturE
B．sEA
C．stAr
D．EArth