雅思阅读长难句练习每日一题（21）

　　本题是继《阅读长难句分析基本原理》后的练习篇，把所掌握的技巧，应用的实际练习当中，进一步夯实自己的阅读能力。

　　练习步骤：

　　step1：划分句子结构，找句子主干

　　step2: 确定修饰词，修饰短语或修饰从句的修饰关系

　　step3: 确定代词指代对象

　　剑桥雅思9

　　Reading Passage 2

　　长难句：However, when we look at the 100 billion stars in our galaxy (the Milky Way), and 100 billion galaxies in the observable Universe, it seems inconceivable that at least one of these planets does not have a life form on it; in fact, the best educated guess we can make, using the little that we do know about the conditions for carbon-based life, leads us to estimate that perhaps one in 100,000 stars might have a life-bearing planet orbiting it.