引出原因的英语句型

　　例句：

　　1、Why do researchers from MIT predict that by the middle of the century, more than half of humanity will live in water-stressed areas? One reason is that as the world’s population grows larger and richer, it uses more water. Another is climate change, which accelerates hydrologic cycles, making wet places wetter and dry places drier.

　　一个原因是随着世界人口增长，人口越来越富裕，它需要更多的水。另一个原因是气候变化，它加速了水文循环，使潮湿的地方更加潮湿，干燥的地方更干燥。

　　2、It is back in fashion for several reasons. Some firms need to repair the damage from the pandemic. The tech boom means unicorns can go public at sky-high valuations. There are other factors, too. More Chinese firms are coming of age.

　　它再次流行有几个原因。一些公司需要补救新冠大流行造成的损害。科技繁荣意味着独角兽企业可以以极高的估值上市。还有其他因素。越来越多的中国企业正走向成熟