There are great many reasons for studying what philosophers 1.________ have said in the past. One is that we cannot separate the history of philosophy from which of science. Philosophy is 2.________ large discussion about matters on which few people are quite 3.________ certain, and those few hold opposite opinions. As knowledge increases,philosophy buds off the sciences. For an example, in the ancient world and the Middle Ages 4.________ philosophers discussed motion. Aristotle and St. Thomas Aquinas taught that a moving body would slow down until a force 5.________ were constantly applied to it. They were wrong. It goes on moving unless something slows it down. But they had gooarguments on their side, and if we study these, and the experiments which proved them right this will help us to distinguish truth 6.________ from false in the scientific controversies of today. 7.________ We also see how different philosopher reflects the social 8.________ life of his day. Plato and Aristotle, in the slave-owning society of ancient Greece, thought man’s highest state was contemplation rather than activity. In the Middle Ages St. Thomas believed a regular feudal system of nine ranks of angels. Herbert 9.________ Spencer, in the time of free competition between capitalists, found the key to progress as the survival of the fittest. Thus 10.________ Marxism is seen to fit into its place as the philosophy for the workers, the only class with a future.1. are ∧ great → a
a great many为固定搭配，修饰可数名词，意为“很多，大量”，后面的名词用复数形式。
2. which → that
that这里做代词，指代前文已经提到的“history”一词，而which可做疑问代词或定语从句的引导词，代这里不能用。
3. large → largely
largely这里是副词，意为“在很大程度上”，如果有人打算把large考虑成修饰discussion的形容词，那么，前边势必加冠词a或the,但没有large discussion的说法，所以这里只能把large改换成副词.
4. an → /
for example是固定搭配，意为“例如”，中间不加不定冠词an。
5. until → unless
until常和not连用，形成not…until句式，所以not是检验until是否用对的一个标志。这句在说：“亚里士多德和圣托马斯·阿奎那都认为一个运动的物体除非给它不停地使力，否则它就会停下来”。unless这里是“除非”的意思。
6. right → wrong
这句话说“但是他们那一方面有很好的论证。如果我们研究这些论述和证明这些说法是错误的那些实验，那么我们就会辨清今日科学纠纷的真与假”。根据上下文判断，这里应是wrong。
7. false → falsehood
这里需要一个名词，因此把false改为falsehood。
8. different → every
这句谓语动词和主语均为第三人称单数，而用different修饰的名词一般用复数形式，因此需要改变different。再看下文，列举了诸位哲学家，因此可把different 改为every，既不妨碍句子意思，又符合语法规则。
9. believed ∧ a → in
believe in 意为“相信”，后常接名词，而believe则为“相信或认为”，后常接从句，因此加上一个介词in。
10. as → in
此句意为“斯宾塞在资本主义自由竞争时期，发现进步的关键在于适者生存”，此句的另一表达方式为“Spencer, in the time of free competition between capitalists, found the survival of the fittest as the key to progress.”而按现有语序，需把as改成in。
