The current period of global warming that Earth is undergoing is caused by certain gases in the atmosphere,notably carbon dioxide. 现在地球正经历的全球暖化是由大气层中天然气所引起,尤其是二氧化碳 这种同一句出现两个is 常常会突然间看不懂耶... 这是什么文法阿?
that Earth is undergoing 是用来形容global warning的这句的主词是global warning,第二个is才是主要的be动词结构其实就解读为 global warning is caused by...什么样的global warning呢? that Earth is undergoing这坨叫做子句,想成是依附在global warning下类似形容词的东西二楼没必要那么不客气吧,不屑回答就别回,人家问得很诚肯