146. The family is a co-operative enterprise for which it is difficult to lay down rules, because each family, needs to work out its own ways for solving its own problems.
　　147. Besides serving the indefinite needs of its native speakers, English is a language in which some of important works in science, technology, and other fields are being produced, and not always by native speakers.
　　148. And someone with a history of doing more rather than less will go into old age more cognitively sound than someone who has not had an active mind.
　　149. Perfectionists struggle over little things at the cost of something larger they work toward.
　　150. Men are naturally most impressed by diseases which have obvious signs, yet some of their worst enemies slowly approach them unnoticed.

　　参考译文：
　　146．家庭就像是一个合作式的企业一样，很难制定统一的规则，因为每个家庭都需要自己的独特的解决问题的办法。
　　147．除了以英语为母语的人大量地使用英语外，很多重要的科学、技术文献也是由英语写成，而且作者不仅仅是以英语为母语的人。
　　148．比起那些头脑不活跃的人来说，年轻时喜欢尽量从事更多工作的人年老后更有认识力。
　　149．完美主义者倾向于为了一点小事花费比事情本身更大的代价去完成。
　　150．人类自然地对于那些有明显特征的疾病有深刻的印象，然而他们最可怕的敌人往往在未被人注意时慢慢接近他们。