阅读下列材料
材料一是万物的尺度，是存在的事物存在的尺度，也是不存在的事物不存在的尺度。
——普罗塔戈拉
材料二阿尔帕说：“……大多数的时候，落在人们头上的幸福或不幸取决于他们自己。”彼特拉克说：“真正的高贵并非天成，而是自为的”。
材料三人生下来就是自由的，人可以说是自由的动物。那么，人民的自由虽可用法律加以保障，但它原是天所赐予的，为任何人所必不可少。如果有人不取这天所赐予的自由，那就是对天犯了大罪，对自己又是莫大的耻辱。
——卢梭《社会契约论》
材料三体现的启蒙精神是什么？当时欧洲社会思想解放运动的核心是什么？
参考答案：
天赋 * * ；理性主义
| About fifty years ago, plant physiologists set out to grow roots by themselves in solutions in laboratory flasks. The scientists found that the nutrition of isolated roots was quite simple. They required sugar and the usual minerals and vitamins. However, they did not require organic nitrogen compounds. These roots got along fine on mineral inorganic nitrogen. Roots are capable of making their own proteins and other organic compounds. These activities by roots require energy, of course. The process of respiration uses sugar to make the high energy compound ATP, which drives the biochemical reactions. Respiration also requires oxygen. Highly active roots require a good deal of oxygen. The study of isolated roots has provided an understanding of the relationship between shoots and roots in intact plants. The leaves of the shoots provide the roots with sugar and vitamins, and the roots provide the shoots with water and minerals. In addition, roots can provide the shoots with organic nitrogen compounds. This comes in handy for the growth of buds in the early spring when leaves are not yet functioning. Once leaves begin photosynthesizing, they produce protein, but only mature leaves can "export" protein to the rest of the plant in the form of amino acids. |
Which of the following best describes the organization of the passage
A．The results of two experiments are compared.
B．A generalization is made, and several examples of it are given.
C．The findings of an experiment are explained.
D．A hypothesis is presented, and several means of proving it are suggested.