1. The hydrologic cycle，a major topic in this science，is the complete cycle of phenomena through which water passes，beginning as atmospheric water vapor，passing into liquid and solid form as precipitation，thence along and into the ground surface，and finally again returning to the form of atmospheric water vapor by means of evaporation and transpiration.
　　水文循環(huán)（hydrologic cycle），作為該學科中的一個主要課題，指的是水所經(jīng)過的諸現(xiàn)象的整個循環(huán)過程，開始時是作為大氣中的水蒸氣，轉(zhuǎn)而作為雨、雪、露、雹一類的降水量經(jīng)過液體和固體形態(tài)，由此而沿著地層表面分布或進入地層表面，比較終通過蒸發(fā)和散發(fā)作用再度回復(fù)到大氣水蒸氣的形態(tài)。
　　難句類型：復(fù)雜修飾、插入語、省略
　　水文循環(huán)（hydrologic cycle），作為該學科中的一個主要課題，指的是水所經(jīng)過的諸現(xiàn)象的整個循環(huán)過程，開始時是作為大氣中的水蒸氣，轉(zhuǎn)而作為雨、雪、露、雹一類的降水量經(jīng)過液體和固體形態(tài)，由此而沿著地層表面分布或進入地層表面，比較終通過蒸發(fā)和散發(fā)作用再度回復(fù)到大氣水蒸氣的形態(tài)。
　　解釋：beginning開始的一系列分詞都是修飾主語The hydrologic cycle的，分別是beginning/passing/passing/returning。值得注意的是，thence along and into the grund surfacee 是thence passing along and entering into the ground surfacee的省略形式，但是看上去意思卻很清楚。類似這樣的省略，是出題者合理地利用了省略來達到改編學術(shù)論文時壓縮文章篇幅的目的。
　　意群訓練：The hydrologic cycle，a major topic in this science，is the complete cycle of phenomena through which water passes，beginning as atmospheric water vapor，passing into liquid and solid form as precipitation，thence along and into the ground surface，and finally again returning to the form of atmospheric water vapor by means of evaporation and transpiration.
　　2. Only when a system possesses natural or artificial boundaries that associate the water within it the hydrologic cycle may the entire system properly be termed hydrogeologic.
　　只有當一個系統(tǒng)擁有自然的或人工形成的邊界來把邊界中的水與水文循環(huán)聯(lián)系起來的時候，才有可能把整個的系統(tǒng)恰當?shù)某蔀榕c水文地質(zhì)學有關(guān)。
　　難句類型：復(fù)雜修飾、倒裝
　　解釋：only放在句首時，主句的情態(tài)動詞may倒裝，這是我們高中就已經(jīng)學過的東西。然而句首的only與倒裝的may距離如此之遠，這在以前卻沒有見過，所以讀上去讓人不習慣。另外一個難點在于，前面的由when所引導的時間狀語從句中，賓語boundaries后面跟了一個定語從句，that associate the water within it with the hydrologic cycle,而且從句中的associate with又被water within it所分開，讀者還要分神去考慮it所指的是什么，所以讀到后面倒裝的may的時候，難免不知所云。
　　意群訓練：Only when a system possesses natural or artificial boundaries that associate the water within it with the hydrologic cycle may the entire system properly be termed hydrogeologic.