一个是结构上的变化，另一个是英语词上的变化
(1)结构上的变化
例：This seems mostly effectively done by supporting a certain amount of research not related to immediate goals but of possible consequence in the future.
给某些与当前目标无关但将来可能产生影响的科研以支持，看来通常能有效地解决这个问题。
(2)用词上的变化
例：Interest in historical methods has arisen less through external challenge to the validity of history as an intellectual discipline and more from internal quarrels among historians themselves.
人们之所以关注历史研究的方法论，主要是因为史学界内部意见不一，其次是因为外界并不认为历史是一门学问。
例：The behavioral sciences have been slow to change partly because the explanatory items often seem to be directly observed and partly because other kinds of explanations have been hard to find.
行为科学之所以发展一直缓慢，部分原因是用来解释行为的依据似乎往往是直接观察到的，部分原因是其他的解释方式一直难以找到。
八、英译汉中的省略关系
(1)动词的省略
例：How well the predictions will be validated by later performance depends upon the amount,reliability,and appropriateness of the information used and on the skill and wisdom with which it is interpreted.
这些预测在多大程度上为后来的表现所证实，这取决于所采用信息的数量、可靠性和适宜性，以及解释这些信息的技能和才智。
(2)名词的省略
例：But even more important,it was the farthest that scientists had been able to look into the past,for what they were seeing were the patterns and structures that existed 15 billion years ago.
但更为重要的是，这是科学家们所能观测到的最遥远的过去的景象，因为他们看到的是150亿年前宇宙云的形状和结构。
(3)修饰语的省略
例：But even more important,it was the farthest that scientists had been able to look into the past,for what they were seeing were the patterns and structures that existed 15 billion years ago.
但更为重要的是，这是科学家们所能观测到的最遥远的过去的景象，因为他们看到的是150亿年前宇宙云的形状和结构。
(4)从句引导词的省略
(5)相同结构的省略
例：Actually， it isn''t,because it assumes that there is an agreed account of human rights,which is something the world does not have.
事实上这种提问并不能把问题讲清楚，因为它是以人们对人权的共同认识为假设的，而这种共同认识并不存在。
