（一）湿地
湿地(di)(di)(di)是地(di)(di)(di)球上有着(zhe)多(duo)功能的(de)、富有生物多(duo)样(yang)性的(de)生态系统,是人类最(zui)重(zhong)要(yao)的(de)生存环境之一。湿地(di)(di)(di)的(de)类型多(duo)种多(duo)样(yang),通常分为自然和(he)人工(gong)两(liang)大类。自然湿地(di)(di)(di)包括沼(zhao)泽地(di)(di)(di)、泥(ni)炭地(di)(di)(di)、湖泊、河流、海滩和(he)盐沼(zhao)等(deng)(deng),人工(gong)湿地(di)(di)(di)主要(yao)的(de)水稻田、水库、池塘(tang)等(deng)(deng)。据资料统计,全(quan)世界共有自然湿地(di)(di)(di)855.8万平方(fang)公(gong)里(li),占陆地(di)(di)(di)面(mian)积的(de)6.4%.
湿地(di)的(de)(de)(de)功能(neng)是多方面的(de)(de)(de)。它可作为直接利用(yong)的(de)(de)(de)水(shui)(shui)源(yuan)或补充(chong)地(di)下水(shui)(shui),又能(neng)有(you)(you)效控制洪水(shui)(shui)和(he)防止(zhi)土(tu)壤沙化,还能(neng)滞(zhi)留沉积物、有(you)(you)毒物、营养物质,从而改(gai)善环境污染；它能(neng)以有(you)(you)机质的(de)(de)(de)形(xing)式(shi)储存碳元素,减(jian)小温室效应,保护海岸(an)不受风(feng)浪侵蚀(shi),提供清洁方便运输方式(shi)……它因有(you)(you)如此众(zhong)多而有(you)(you)效力的(de)(de)(de)功能(neng)而被人们（ ）“自然(ran)之肾(shen)”。湿地(di)还是众(zhong)多植(zhi)物、动物特别是水(shui)(shui)禽生长的(de)(de)(de)乐园,同(tong)时又向人类提供食物（水(shui)(shui)产(chan)品(pin)、禽畜、谷物）、能(neng)源(yuan)（水(shui)(shui)能(neng)、泥炭(tan)、薪柴）、原(yuan)材料（芦苇(wei)、木材、药(yao)用(yong)植(zhi)物）和(he)旅游场所,是人类赖以生存和(he)持续发展(zhan)的(de)(de)(de)重要基础。
湿(shi)(shi)地(di)(di)(di)最有(you)生(sheng)(sheng)(sheng)物(wu)的多样性。仅我(wo)国有(you)记载的湿(shi)(shi)地(di)(di)(di)植(zhi)物(wu)就有(you)2,760余种(zhong)(zhong)(zhong),其(qi)中(zhong)(zhong)(zhong)湿(shi)(shi)地(di)(di)(di)高等植(zhi)物(wu)156科、437属、1,380多种(zhong)(zhong)(zhong)。湿(shi)(shi)地(di)(di)(di)植(zhi)物(wu)从(cong)生(sheng)(sheng)(sheng)产环(huan)(huan)境(jing)看(kan),可(ke)分(fen)(fen)为(wei)水生(sheng)(sheng)(sheng)、沼生(sheng)(sheng)(sheng)、湿(shi)(shi)生(sheng)(sheng)(sheng)三类(lei)(lei)；从(cong)植(zhi)物(wu)生(sheng)(sheng)(sheng)活类(lei)(lei)型(xing)(xing)看(kan),有(you)挺水型(xing)(xing)、浮叶型(xing)(xing)、沉水型(xing)(xing)和飘浮型(xing)(xing)等；从(cong)_______看(kan),有(you)的是(shi)(shi)(shi)细弱小(xiao)草,有(you)的是(shi)(shi)(shi)粗(cu)大草本,有(you)的是(shi)(shi)(shi)矮小(xiao)灌木,有(you)的是(shi)(shi)(shi)高大乔(qiao)木。湿(shi)(shi)地(di)(di)(di)动物(wu)的种(zhong)(zhong)(zhong)类(lei)(lei)也异常丰富,我(wo)国已记录的湿(shi)(shi)地(di)(di)(di)动物(wu)有(you)1,500种(zhong)(zhong)(zhong)左(zuo)右（不(bu)含昆虫、无脊椎动物(wu)、真(zhen)菌和微生(sheng)(sheng)(sheng)物(wu)）,其(qi)中(zhong)(zhong)(zhong)水禽大约250种(zhong)(zhong)(zhong),鱼(yu)类(lei)(lei)约1,040种(zhong)(zhong)(zhong)。鱼(yu)类(lei)(lei)中(zhong)(zhong)(zhong)淡水鱼(yu)有(you)500种(zhong)(zhong)(zhong)左(zuo)右,占(zhan)世界(jie)上淡水鱼(yu)类(lei)(lei)总数的80%以上。因(yin)此,无论(lun)从(cong)经济学(xue)还是(shi)(shi)(shi)生(sheng)(sheng)(sheng)态水学(xue)的观点年(nian),湿(shi)(shi)地(di)(di)(di)都是(shi)(shi)(shi)最具(ju)(ju)有(you)价值(zhi)和生(sheng)(sheng)(sheng)产力最高的生(sheng)(sheng)(sheng)态系统。 1. 全文(wen)(wen)的中(zhong)(zhong)(zhong)心句是(shi)(shi)(shi): 2. 文(wen)(wen)中(zhong)(zhong)(zhong)运用了多种(zhong)(zhong)(zhong)说(shuo)明(ming)方法(fa),除“列数字(zi)”外,用得最多的两种(zhong)(zhong)(zhong)是(shi)(shi)(shi):_______、_________ 3. 试用表格显示第(di)1段文(wen)(wen)字(zi)中(zhong)(zhong)(zhong)画横(heng)线的内容。 4. 根据具(ju)(ju)体的语(yu)(yu)(yu)言环(huan)(huan)境(jing),从(cong)“誉为(wei)、称为(wei)、喻(yu)为(wei)、视为(wei)”中(zhong)(zhong)(zhong)选(xuan)词归(gui)位(wei)于(yu)第(di)2段中(zhong)(zhong)(zhong)的括号,最符合语(yu)(yu)(yu)境(jing)的一个(ge)是(shi)(shi)(shi):______________ 5. 人们说(shuo)湿(shi)(shi)地(di)(di)(di)是(shi)(shi)(shi)“自然(ran)之肾”而不(bu)说(shuo)它是(shi)(shi)(shi)“自然(ran)之肺(fei)”,这是(shi)(shi)(shi)有(you)道(dao)理的。第(di)2段文(wen)(wen)字(zi)中(zhong)(zhong)(zhong)有(you)个(ge)句子能基本上表现(xian)这种(zhong)(zhong)(zhong)道(dao)理,这个(ge)句子说(shuo)的是(shi)(shi)(shi):湿(shi)(shi)地(di)(di)(di)能__________________ 6. 要理解第(di)3段文(wen)(wen)字(zi)中(zhong)(zhong)(zhong)“分(fen)(fen)说(shuo)”部分(fen)(fen)的层(ceng)次与内容,应抓住(zhu)的两个(ge)关键语(yu)(yu)(yu)句是(shi)(shi)(shi): ① ② 7. 根据具(ju)(ju)体的语(yu)(yu)(yu)言环(huan)(huan)境(jing),在第(di)3段文(wen)(wen)字(zi)的横(heng)线上应填(tian)进(jin)的内容是(shi)(shi)(shi):_______
第3段文字(zi)在数字(zi)运(yun)用上有什(shen)么(me)特点？试举两例说明(ming)。
