句子之间的关系多种多样，常见的有：并列关系、因果关系、递进关系、转折关系和相互解释关系。
Women could and did play a part in this process of settlement. Iceland， for instance， was uninhabited， and a permanent population could only be established if women also made the journey there. (后一句的具体事例为前一句提供说明与解释)
People borrowed more and more money so that they could buy these shares. Because of this， the American people started to believe that share prices could only go up further. (“because of”明显的因果关系)
Astronomy is a science that deals with all the celestial bodies in the universe. Astronomy includes the study of planets and their satellites， comets and meteors， stars and interstellar matter， star systems and clusters. (后一句是对前一句celestial bodies 的进一步解释)
Previously it was believed that due to the Archaeopteryx’s (始祖鸟) underdeveloped anatomy， it would not have been able to fly. However， research by the London Natural History Museum into its brain developed and that it had good vision and a good sense of balance — all the requirements for a creature to be able to fly. (“However”转折对比)
阅读时，我们可以根据段落中出现的一些信号词(Signal Words)来判断句子与句子之间的关系，掌握段落发展线索，来调整阅读速度，提高阅读质量。