今天我们来看这样一个句子：

　　Estimates indicate that the aquifer contains enough water to fill Lake Huron, but unfortunately, under the semiarid climatic conditions that presently exist in the region, rates of addition to the aquifer are minimal, amounting to about half a centimeter a year. (41, TPO3)

　　aquifer /'ækwɪfə/ n. 含水土层

　　semiarid /ˌsem(a)ɪ'ærɪd/ adj. 半干旱的

　　我是分解线，大家先自己分析哦

　　Estimates indicate (that the aquifer contains enough water to fill Lake Huron), but unfortunately, (under the semiarid climatic conditions) (that presently exist in the region), rates of addition to the aquifer are minimal, (amounting to about half a centimeter a year. )

　　分析：

　　修饰一：(under the semiarid climatic conditions)，介词短语，修饰后面红色主干部分

　　中文：在半干旱气候条件下

　　修饰二：(that presently exist in the region)，从句，修饰conditions

　　中文：现在存在于这个地区

　　修饰三：(amounting to about half a centimeter a year. ) ，非谓语动词，修饰前面红色主干

　　中文：总计大约一年50毫米

　　主干：rates ofaddition to the aquifer are minimal

　　中文：蓄水层的补水率很小

　　参考翻译：

　　估计表明：蓄水层包含充足的水去填满Huron湖。但很不幸，在目前这个地区半干旱气候条件下，蓄水层的补水率很小，总计大约一年50毫米。

　　这个句子的主要修饰成分就是介词短语、从句、非谓语动词，大家务必想清楚，每一个修饰成分修饰的是什么，才能看清楚这个句子的结构。