2012年12月大学英语六级考试阅读疑难杂句4
But science does provide us with the best available guide to the future, and it is critical that our nation and the world base important policies on the best judgments that science can provide concerning the future consequences of present actions.
【词汇突破】critical 重要的，
concerning 关于
【主干识别】and连接两个完整的并列句。第一个句子主干为： science does provide us with the best available guide to the future.第二个句子主干为：it is critical that +主语从句。
【其他成分】our nation and the world base important policies on the best judgments that science can provide concerning the future consequences of present actions主语从句
【微观解析】由于表语是critical表示重要性，在从句中用了“shoud +动词原型”的虚拟语气动词形式，should 被省略了;that science can provide定语从句修饰judgment;concerning the future consequences of present actions.现在分词短语也是在修饰judgment。
