文档介绍：Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. 13 只有一个地球 Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. 只有一个地球默读课文, 跟同学讨论: 课文写了关于地球的哪几个方面的内容? Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. 地球的渺小自然资源有限目前人类无法移居人类应该保护地球 Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. 自然资源有限? 1 “不可再生资源面临枯竭”?据 2000 年 12 月 30 日《世界能源导报》报道, 我国能源资源的形势十分严峻。经探明:煤炭可开采年限为 54 ~ 81 年,石油可开采年限为 15 ~ 20 年,天然气可开采年限为 28 ~ 58 年……随着煤炭等资源开采量的逐年攀升,煤炭开采的实际年限,远远比现实严峻。 Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. 2 “可再生资源遭到破坏”?随意毁坏自然资源,不顾后果地滥用化学品,造成一系列生态灾难…… Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. 人类目前无法移居?科学家已经证明, 至少在以地球为中心的 40 万亿千米的范围内,没有适合人类居住的第二个星球。人类不能指望在破坏了地球以后再移居到别的星球上去。? Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspos