单项选择题 New Foods and the New World In the last 500 years, nothing about people - not their clothes, ideas, or languages- has changed as much as what they eat. The original chocolate drink was made from the seeds of the cocoa tree (可可树) by South American Indians. The Spanish introduced it to the rest of the world during the 1500's. And although it was very expensive, it quickly became fashionable. In London, shops where chocolate drinks were served became important meeting places. Some still exist today.The potato is also from the New World. Around 1600, the Spanish brought it from Peru to Europe, where it soon was widely grown. Ireland became so dependent on it that thousands of Irish people starved when the crop failed during the 'Potato Famine (饥荒)'of 1845-1846, and thousands more were forced to leave their homeland and move to America.There are many other foods that have traveled from South America to the Old World. But some others went in the opposite direction. Brazil is now the world's largest grower of coffee, and coffee is an important crop in Colombia and other South American countries. But it is native to Ethiopia, a country in Africa .it was first made into a drink by Arabs during the 1400's.According to an Arabic legend, coffee was discovered when a person named Kaldi noticed that his goats were attracted to the red berries on a coffee bush. He tried one and experienced the 'wide-awake' feeling that one third of the world's population now starts the day with. 第 31 题 According to the passage, which of the following has changed the most in the last 500 years?A．Food.B．Clothing.C．Ideology.D．Language.
未知题型 9月，病鱖在池边无目标游动。剖检可见肝脏偏白且有淤血点，肠内充满黄色粘液，脾、肾肿大。同池混养的草鱼无异常。诊断最适宜的取样的部位是（）
单项选择题 Dark Forces Dominate Universe The earth, moon, sun and all visible stars in the sky make up less than one percent of the universe, .Almost all the rest is dark matter and dark energy, unknown forces that___________(51) astronomers.Observations in recent years have changed the basic___________ (52) of how the universe evolved and have indicated how little is known about the major forces and substances that___________(53) our world.Astronomers now know that luminous发光的) matter---stars, planets and hot gas--accounts___________ (54)only about 0.4 percent of the universe. Non-luminous components, such as black holes and intergalactic (星系间的) gas, ___________ (55)up 3.6 percent. The rest is either dark matter, about 23 percent, or dark energy, about 73 percent.Dark matter, sometimes___________(56) 'cold dark matter,' has been known for some time. Only recently have researchers come to understand the key role it___________(57) in the formation of stars, planets and even people.'We ___________ (58) our very existence to dark matter,' said physicist Paul Steinhardt and a co-author of a review on dark matter which (59) not long ago in the journal Science.'Dark matter dominated the structure___________ (60) in the early universe,'Steinhardt saiD．'For the first few billion years dark matter contained most of the mass of the universe. You can think of ordinary matter ___________ (61) a froth (泡沫) of an ocean of dark matter. The dark matter clumps (结成块) and the ordinary matter falls into it.That___________ (52) to the formation of the stars and galaxies (星系.'Without dark matter, 'there would be virtually no structures in the universe.'The nature of dark matter is___________ (63). It cannot be seen or detected directly.Astronomers know it is there because of its___________ (64) on celestial (天体的)objects that can be seen and measured.But the most dominating force of all in the universe is called dark energy, a recently ___________ (65) power that astronomers say is causing the galaxies in the universe to separate at a faster and faster speed. 第 51 题A．worry B．moveC．puzzleD．reject