只    有    一    个    地    球   

 据    有    幸    飞    上    太    空    的    宇    航    员    介    绍   , 他    们    在    天    际    遨    游    时    遥    望    地    球   , 映    入    眼    帘    的    是    一    个    晶    莹    的    球    体   , 上    面    蓝    色    和    白    色    的    纹    痕    相    互    交    错   , 周    围    裹    着    一    层    薄    薄    的    水    蓝    色    纱    衣   。 地    球   , 这    位    人    类    的    母    亲   , 这    个    生    命    的    摇    篮   , 是    那    样    美    丽    壮    观   , 和    蔼    可    亲   
 但    是   , 在    群    星    璀    璨    的    宇    宙    中   , 地    球    是    一    个    半    径    约    为    千    米    的    星    球   。 同    茫    茫    宇    宙    相    比   , 地    球    是    渺    小    的   。 它    只    有    这    么    大   , 不    会    再    长    大   
 地    球    所    拥    有    的    自    然    资    源    也    是    有    限    的   。 拿    矿    产    资    源    来    说   , 它    不    是    谁    的    恩    赐   , 而    是    经    过    几    百    万    年   , 甚    至    几    亿    年    的    地    质    变    化    才    形    成    的   。 地    球    是    无    私    的   , 它    向    人    类    慷    慨    地    提    供    矿    产    资    源   。 但    是   , 如    果    不    加    节    制    地    开    采   , 必    将    加    速    地    球    上    矿    产    资    源    的    枯    竭   
 人    类    生    活    所    需    要    的    水    资    源   、 土    地    资    源   、 生    物    资    源    等   , 本    来    是    可    以    不    断    再    生   , 长    期    给    人    类    作    贡    献    的   。 但    是   , 因    为    人    们    随    意    毁    坏    自    然    资    源   , 不    顾    后    果    地    滥    用    化    学    品   , 不    但    使    它    们    不    能    再    生   , 还    造    成    了    一    系    列    生    态    灾    难   , 给    人    类    生    存    带    来    了    严    重    的    威    胁   
 有    人    会    说   , 宇    宙    空    间    不    是    大    得    很    吗   , 那    里    有    数    不    清    的    星    球   , 在     地    球    资    源    枯    竭    的    时    候   , 我    们    不    能    移    居    到    别    的    星    球    上    去    吗   ?
 科    学    家    已    经    证    明   , 至    少    在    以    地    球    为    中    心    的    万    亿    千    米    的    范    围    内   , 没    有    适    合    人    类    居    住    的    第    二    个    星    球   。 人    类    不    能    指    望    地    球    被    破    坏    以    后    再    移    居    到    别    的    星    球    上    去   
 本    文    作    者    李    剑    波   、 蔡    士    魁   ,  选    作    课    文    时    有    改    动   
 不    错   , 科    学    家    们    提    出    了    许    多    设    想   , 例    如   , 在    火    星    或    者    月    球    上    建    造    移    民    基    地   。 但    是   , 即    使    这    些    设    想    能    实    现   , 也    是    遥    远    的    事    情   。 再    说   , 又    有    多    少    人    能    够    去    居    住    呢   ?
 我    们    这    个    地    球    太    可    爱    了   , 同    时    又    太    容    易    破    碎    了   ! 这    是    宇    航    员     遨    游    太    空    目    睹    地    球    时    发    出    的    感    叹   
 只    有    一    个    地    球   , 如    果    它    被    破    坏    了   , 我    们    别    无    去    处   。 如    果    地    球    上    的    各    种    资    源    都    枯    竭    了   , 我    们    很    难    从    别    的    地    方    得    到    补    充   。 我    们    要    精    心    地    保    护    地    球   , 保    护    地    球    的    生    态    环    境   。 让    地    球    更    好    地    造    福    于    我    们    的    子    孙    后    代    吧   !
 因    为    人    们    随    意    毁    坏    自    然    资    源   , 不    顾    后    果    地    滥    用    化    学    品   , 不    但    使    它    们    不    能    再    生   , 还    造    成    了    一    系    列    生    态    灾    难   , 给    人    类    生    存    带    来    了    严    重    的    威    胁   

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