名词从句是
三种句子来充当四种成分。(3，4)
上面说到的SAT语法知识中的名词从句就是用一个完整句子充当另一个句子的某种句子成分便构成了具体某一名词从句。
这三种句子不是直接放在另个句子中作成分，而是要做以下调整：
1)用陈述句作成分时，要在句首加
2)用一般问句作成分时，先将疑问句换成语序，然后在句首加
3)用特殊问句作成分时，只需将疑问句换成正常语序。
下面是95年1月份的阅读真题，来感受下几个难句吧，若搞定名词从句，那它们也就是小儿科。
It is a curious paradox that we think of the physical sciences as “hard”， the social sciences as “soft，” and the biological sciences as somewhere in between. This is interpreted to mean that our knowledge of physical system is more certain than our knowledge of biological systems， and these in turn are more certain than our knowledge of social systems. In terms of our capacity of sample the relevant universes， however， and the probability that our images of these universes are at least approximately correct， one suspects that a reverse order is more reasonable。