1. 表示因果类关键词：as a result, result in, result from, lead to, because of, due to, contribute to, owning to, hence, since, accordingly, consequently, therefore, in that, etc.
2. 表示转折类关键词：despite, in spite of, but, although, though, while, yet, otherwise, on the other hand, however, nevertheless, nonetheless, etc.
3. 表示比较类关键词：more, than, less, the least, the most, prefer, equally, likewise, similarly, in comparison, as…as, etc.
4. 表示并列类关键词：first, second…finally, and, or, as well as, one… the other,not…nor…, etc.
And the future- If we are to believe the forecasts, it is predicted that two thirds of the world population will be without fresh water by 2025. But for a growing number of regions of the world the future if already with us. While some areas are devastated by flooding, scarcity of water in many other places is causing conflict. The state of Texas in the United States of America is suffering a shortage of water with the Rio Grande falling to reach the Gulf of Mexico for the first time in 50 years in the spring of 2000, pitting region against region as they vie for water sources. With many parts of the globe running dry through drought and increased water consumption, there is now talk of water being the new oil.
分析：此段开头先提出了“根据预测到2025年世界上将有三分之二的人口喝不到淡水”接着分别用转折词but，while进一步提出某些地区由于洪水泛滥带来的破坏，在其它许多地方水的缺失已变得日趋严峻。接着从“The state of Texas…water sources”通过一个细节举例 (德克萨斯州的人们正在饱受缺水之苦)来作进一步说明。