一个没有绿树的世界(A World Without Trs)hav you vr imagind a world without trs? try it, and you will s th whol world dry up and look lik a brokn tortois shll. at night, th tmpratur would drop sharply. living craturs could not run away and it would b as if thy livd in hll.thr ar som ffctiv stps w can tak now to protct trs. first, strict laws must b nforcd. scond, th govrnmnt should offr subsidis to popl who plant trs.most important of all, vry citizn must dvlop an awarnss of th importanc of trs and rmmbr: no trs mans no living things.