1.因果关系
因：because、because of、for、as、since、in that、on account of、with
果：so、so that、therefore、thereby、as a result、hence、thus、consequently、accordingly
因果关系除了传统意义上的'显性因果表达词外，隐性的因果同样是不可忽略的一个重要部分。
隐性因果：
A 导致(因-果)：cause、reason、lead to、give rise to、result in、render、make、let、ask、push、stimulate、fuel、produce
如：The increased presures of expanding population have led to the removal of woody plants so that many cities and tow are surrounded by large areas completely lacking in trees.
在这段话中，有lead to表示了导致的意思，即结果，而so that更进一步表示了后面的结果，所以可以充分判定这段话有因果关系的逻辑。
B 由 而来(果-因)：result from、derive from、originate from、initiate from、stem from、be attributable to
如： The extreme serioue of desertification results from the vast areas of land and tremendous numbers of people affected，as well as from the great difficulty of reversing or even slowing the proce.
在这段话中，根据result from可以推断出有因果关系，那如果是解释句子题时，选项中有因果关系就可以优先考虑。
