第一反应英语

第一句是一个复合句，Groundwater是主语，Groundwater is the word是一个句子。used to 。describe water修饰word，是定语；saturates the ground是修饰water的定语。filling all the available space是同位语。第二句是一个正常的句子。第三句是一个复合句。circulates as part of the water cycle修饰groundwater。第四句依然是一个复合句，has soaked以后的内容全是修饰第二个water。第五句是一个正常的句子，before后面是同位语从句。最后一句是主语后置，it指代的是there can be enough space in the "solid" ground underfoot to hold all this water。纯分析，望采纳，谢谢！！！

when it comes to...my first thought would be...e.g. When it comes to pornstars, my first thought would be Miss Bitoni

At the mere mention of..., xxx

应该说： Hello,who are you?What's up? Hi,nice to see you(如果你不认识他的话）