1 ) 信号词之原因

例如reason, cause, since, in that, as, because, thanks to, owing to, 解释说明某一事物或事件，往往会蕴含重要信息。如 'since the lifetime of a planet like ours is several billion years, we can expect that … ' 该句是之后简答题 'what is the life expectancy of Earth' 的答案信息来源，如果考生只定位Earth, 那就很有可能失分，因为原句对Earth 做了同义替换的表述，而 since 这个信号词则提示了答案所在的地方。

2 ) 信号词之结论

例如thus, therefore, so, hence, consequently, as a result, 这些词往往是对前面所论述的总结归纳，例如'Tortoises therefore represent a remarkable double return ’，该句出现在整篇文章的末段首句，很明显是对前文的总结概括，高度浓缩了信息。最后的主旨选择题，就是对该句的改写：'they have made the transition from sea to land more than once ’。

3 ) 信号词之转折

例如however, but, by comparison, nonetheless, nevertheless，这些词往往表示文章观点或方向的重大转变，重点应该关注信号词后面的内容。如‘this definition implies that iconoclasts are different from other people, but more precisely, it is their brains that are different in three distinct ways ’，前半句指出iconoclasts 异于常人，用but 转折词，强调指出区别的关键地方。这也是选择题‘iconoclasts are distinctive because … ' 的出题方向。

4 ) 信号词之让步

例如although, though, while, whereas, whilst 等连接的句子，后半句才是引出的话题和强调内容。如'He accurately predicted that Venus would cross the face of the Sun in both 1761 and 1769--though he didn't survive to see either ’，前半句讲述他精确预测金星跨越太阳的两次时间，后半句用though 引出让步内容，他没有看到任何一次。判断题中‘Halley observed one transit of the planet Venus ’主要就是以原文定位句的后半句为判断依据。

5 ) 信号词之举例

例如for example, for instance, that is to say, such as, include, 后面引出具体事物的详细例子，同时原文中破折号和冒号也有异曲同工之妙，对前面的内容补充说明。如‘in other worlds, the life form we are looking for may well have two green heads and seven fingers, but it will nevertheless resemble us in that it should communicate with its fellows, be interested in the Universe, live on a planet orbiting a star like our Sun, and perhaps most restrictively, have a chemistry, like us, based on carbon and water.' 整句话都在解释说明该段的第二个假设 'we are looking for a life form that is pretty well like us ’，所举的例子也是判断题‘SETI scientists are trying to find a life form that resembles humans in many ways' 的判断依据。

6 ) 信号词之顺序

例如first, second, finally, eventually, later, then, next 等，体现出文章内容的逻辑性与发展性。如'In discussing whether we are alone, most SETI scientists adopt two ground rules. First, … Second …’，使用first 和second 这两个序数词，清晰逻辑地讲述了两个重要的假设。这两个信号词，也是这篇文章heading 题型段落大意的重点提示。

7 ) 信号词之比较级

例如more, most, -est, best, better,exclusively, extremely, superior, preferable，表示事物之间的比较，也是文章要强调的地方。如‘one part is a targeted search using the world's largest radio telescopes, the American-operated telescope ’，该句的the world's largest radio telescopes 对应了题目中the world's most powerful radio telescopes，答案信息就在这里。