[10-20 18:10:12] 来源：http://www.67xuexi.com 高二英语 阅读：85563次
By 1846, he had published an article describing his voyage. He also began to think seriously about evolution and natural selection, and wrote two essays describing his ideas. He did not publish these essays because he realized his ideas proved the Bible’s theory of creation was wrong, and he was worried about the anger and troubles they would cause.
Darwin spent the following years developing his theories and making them perfect. In 1859 he published them in The Origin of Species(《物种起源》). It caused a huge row because it seemed to deny what the Bible said. His The Descent of Man(《人类的由来》), 1871, pointed out that mankind had come from the same ancestor. Darwin was upset by the opposition. Other scientists agreed with his ideas and took up his cause. The Church prohibited the teaching of the Theory of Evolution(进化论) in some countries. However, today most people believe that Darwin was right.
27. Miracle in the rice field
It is said that every scientist has a childhood dream for his or her future success. For Yuan Longpin, known as the “father of hybrid rice(杂交水稻)”, the dream is that he cultivates rice as huge as peanuts, and farmers can have a rest in the cool shadow of big rice plants.
Yuan Longpin was born into a poor family in 1931. Upon graduating from the Southwestern Agricultural College(西南农业学院) in 1953, he began his teaching career at an agriculture school and has since devoted himself to agricultural education and research.
He came up with the idea of hybrid rice for the first time in the 1960s. In the early 1970s, he succeeded in developing the world’s first high-yield hybrid rice. Of great importance is his pioneering work, which has established China’s position of world leadership in this area.
The UN Food and Agriculture Organization(FAO)(联合国粮食与农业组织) has decided to get involved in the work of spreading the coverage of Yuan’s high-yield hybrid rice, which it considers the best way to increase the world’s grain output.
In the following years, increasing grain output of hybrid rice further showed the success of Yuan Longpin’s research. This made him firmly believe that China can surely feed her large population with her limited cultivated land.
This breakthrough in rice cultivation has significantly contributed to solving the food problem in China and the rest of the world. Yuan’s amazing achievement has won him a great many awards and honours from the United Nations and worldwide.
However, even with such a great achievement, Yuan won’t take a break. In his mind there always exist a dream, more practical than that of his youth, that popularizing the new hybrid rice with higher yields around the world can eliminate starvation on Earth. “If the new hybrid rice were grown in the world’s remaining fields, the present grain output around the world would be more than doubled. This can solve the grain shortage,” said the scientist.
Some people estimate Yuan’s actual fortune might make him one of the richest people in China. But he doesn’t know for sure himself, for he seems to care for nothing more than his research.
In spite of his busy research work, Yuan Longpin has managed to keep some hobbies in his spare time, including reading books and listening to music. He enjoys daily motor cycling and sometimes playing the violin.
28. Newton’s three important laws
Things that move obey certain laws. Three important laws of motion were established by Isaac Newton (1642～1727) (英国物理学家、天文学家和数学家，被公认为有史以来最伟大和影响最深远的科学家).
NEWTON Ⅰ: INERTIA(惯性定律)
Newton’s first law of motion seems simple: Objects at rest tend to remain at rest, while moving ones continue to move at a uniform speed in a straight line---unless acted upon by an outside force. This resistance(阻力) to change is called inertia, and it explains a lot of everyday experienced no matter where you happen to live.
One is that when the car or airplane you’re in begins to move, your body is pushed back against the seat. That is, it tends to remain at rest despite the forward-moving force of the vehicle transferred to you through the seat. Another aspect of this law shows that the normal courses for freely moving objects is a straight line. That explains why, when you whirl(迅速旋转) something around your head---such as a ball on a string---and then let it go, the ball flies straight. It neither keeps circling your head nor does it move off in a sweeping(做大幅度弧线形运动的) curve(曲线).
NEWTON Ⅱ: F=MA
Newton’s second law relates the amount of force needed to move an object to the object’s mass and tits acceleration(加速度).
Push a child in a swing, or ride a planet around the sun, and you’re using Newton’s second law of motion, which states that whenever you want to change the speed or direction of something, you have to apply an appropriate force. The bigger the mass or the larger the intended acceleration, the greater the necessary force. This law’s formula allows engineers to calculate what’s required to launch a jet fighter(喷气式战斗机) from an aircraft carrier(航空母舰), or how strong a seat belt must be to restrain(抑制，控制), say, a 160-pound person when his car stops suddenly while travelling at 60 mph.
上一页 [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] 下一页