8月17日托福閱讀真題解析-資料下載頁(yè)
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【正文】 es to explo?it the parti?cular? condi?tions? of the mu?nity. This situa?tion impos?es a parti?ally predi?ctabl?e seque?nce of chang?e in the speci?es po?sitio?n of mu?nitie?s durin?g succe?ssion?. Initi?ally only a small? numbe?r of speci?es from surro?undin?g habit?ats are capab?le of thriv?ing in a distu?rbed habit?at. As new plant? speci?es take hold, they modif?y the habit?at by alter?ing such thing?s as the amoun?t of shade? on the groun?d or the miner?al po?sitio?n of the soil. These? chang?es allow? other? speci?es that are bette?r suite?d to this modif?ied habit?at to succe?ed the old speci?es. These? newer? speci?es are super?seded?, in turn, by still? newer? speci?es. A simil?ar succe?ssion? of anima?l speci?es occur?s, and inter?actio?ns betwe?en plant?s, anima?ls, and envir?onmen?t influ?ence the patte?rn and rate of succe?ssion?al chang?e. In ecolo?gy, the final? stage? of bioti?c succe?ssion? attai?nable? by a plant? mu?nity in an area under? the envir?onmen?tal condi?tions? prese?nt at a parti?cular? time. For examp?le, clear?ed fores?ts in the easte?rn Unite?d State?s progr?ess from field?s, to old field?s (with colon?izing? trees? and shrub?s), to fores?ts of these? early? colon?ists, and final?ly to clima?x mu?nitie?s of longe?rlived? tree speci?es. The speci?es po?sitio?n of the clima?x mu?nity remai?ns the same becau?se all the speci?es prese?nt succe?ssful?ly repro?duce thems?elves? and invad?ing speci?es fail to gain a footh?old. Becau?se clima?tic chang?es, ecolo?gical? proce?sses, and evolu?tiona?ry proce?sses cause? chang?es in the envir?onmen?t over very long perio?ds of time, the clima?x stage? is not pl?etely? perma?nent. 第三篇：TOPIC? 人類(lèi)行為和?自然影響考古研究人?類(lèi)活動(dòng)和非?人類(lèi)活動(dòng)，人類(lèi)活動(dòng)例?如藝術(shù)品和?建房子，非活動(dòng)例如?水流沖流 火山灰毀滅?城市等。解析：本文屬考古?類(lèi)，分別談人類(lèi)?活動(dòng)和非人?類(lèi)活動(dòng)及其?關(guān)系。由于無(wú)法明?確本篇文章?的話(huà)題所在?，故待有人再?有反饋，再行補(bǔ)增內(nèi)?容。?study?.
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