阅读过程中常见的几类“信号词”：
1.以下词组提示下文所涉及的重要信息：
The main / important point / conclusion / reason….
The point to note here…
2.以下词组提示了下文的结构框架：
There are three major reasons…
3.but 和 however表示对比，常常用来提示重要信息，例如：
The rising birth rate is not due to increased fertility, but to a sharp decline in the death rate.
4.在文中提问可以突出问题后的答案，提示读者答案中有重要信息，例如：
Why is a piped water supply so important? Disease due to contaminated water is a common cause of death in childhood.
5.有时，为了保证读者完全理解自己的观点，作者会在文中反复提出自己的观点，例如：
Death control can be achieved autonomously. In other words, the death rate can be cut without anything else changing.
