单选题Music has been called both the most mathematical-----the most abstract of the arts.

单选题Air, which (it is) a mixture of elements oxygen and nitrogen (and compounds) water and carbon dioxide, also (contains) small quantities of (many other) substances.

单选题The author mentions Vivaldi and Tartini in line 20 as examples of composers whose music

单选题Scientists have traditionally (classified) plants by (grouping them) according to similarities in their overall (appear), their internal structure, and the form of their (reproductive) organs.

单选题(a)Shehascompletedherproject(b)Sheneedssomehelpfinishingtheproject(c)Hereconomicsclassnolongermeets(d)Themanshouldnottouchtheprojectuntilitisfinished

单选题Almost ....... substances expand in volume when heated and contract when cooled.

单选题The Actor's Studio, a professional actors' workshop in New York City, provides______where actors can work together without the pressure of commercial production. A. a place and B. a place C. so that a place D. a place is

单选题Modern digital synthesizers, based on microprocessors, are virtually unlimited in the number and range of musical sounds it can produce.

单选题Fuel is (any) substance or material (that reacts) chemically (with) another substance or material toproduce (hot).

单选题Great pain and swelling characterize both sprains and fractures, but-------the affected part and unnatural twisting often indicate a bone break.

单选题Whydoesthestudentgotoseetheadvisor?

单选题If Earth did not rotate, differences in air pressure would be —, with winds blowing from high-pressure to low-pressure areas.

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单选题The Civil War Involvement in a war is painful to any nation. No nation wants to send its young people to fight and die. It is even worse when the war is fought within the country, but worst of all is when a country finds itself divided, and people of the same nation fight each other. In America"s history, the most painful period is surely the Civil War. The Civil War was fought for many complex reasons. Probably the most important was the issue of slavery. 1) The Southern states, dependent on slaves for producing cotton, wanted to continue the practice of slavery, while the industrialized Northern states wanted to abolish it. The issue of States" Rights, the right of individual states to make laws without interference from the national government, was also very divisive. There were even basic cultural differences that caused friction between Northerners and Southerners. All of these factors led to a war between the North and South, which turned out to be the bloodiest in the nation"s history. Both sides suffered terribly in the war. Families were torn apart as fathers, sons, and brothers chose different sides. Hundreds of thousands of young men died on both sides. The city of Atlanta was burned to the ground. Fortunes were ruined and the economy of the Southern states was wrecked. People on both sides suffered, and that suffering was worse because it was inflicted by their countrymen and brothers. Shortly after the war, a bitter Southerner assassinated the beloved president Abraham Lincoln. After four bloody, terrible years, the North won the war and the country was reunited. The slaves were freed and the nation set about rebuilding. 2) Historians will always argue whether or not the Civil War could have been avoided, and what its long term benefits have been. There can be no argument, however, that the Civil War was the most painful period in America"s history. The American Civil War began with the surrender of the Northern army of the garrison at Fort Sumter. 3) This military post was located in the city of Charleston, the hotbed of Southern sedition, and thus capturing it was a huge morale boost for the Southern states. The Southern cavalry boasted of a short two-months win over the Northern states. Yet reality would be different. 4) After several more buoyant victories, the Southern army became so cocky it started making mistakes. Rather than focusing on solidifying their wins, soldiers dispersed in a futile attempt to capture many Northern prisoners. The army disintegrated, and it was not long before the industrialized North regained its strength and delivered the fatal blow to the South at the battle of Gettysburg. Instead of the predicted two months, the South lost the war after 4 bloody years of combat. Glossary Civil War: the war in the United States between the Union and the Confederacy from 1861 to 1865 slavery: the practice of owning slaves interference: the act of hindering or obstructing or impeding Southerner: a native or inhabitant of the south, especially the southern United States

单选题The law of biogenesis is the principle what all living organisms are derived from a parent or parents.

单选题The reasons for the migration from rural to urban life were exploitation and lack of economic opportunity. The family members who would not inherit a share in the property were exploited by the laws of inheritance. The system was particularly hard on women, who usually did not share in the ownership of the farm and who rarely were paid for their labor. The workday for women was even more demanding than it was for men. Women were responsible for the kitchen garden and the small livestock as well as the care of the family. Unmarried women increasingly left the farm in search of economic opportunity in the factories that processed fish or farm products. 4. It can be inferred from the passage that women under this system

单选题Cancer and Chemicals Last year, California governor George Deukmejian called together many of the state's best scientific minds to begin implementing Proposition 65, the state's Safe Drinking Water and Toxic Enforcement Act. This new law bans industries from discharging chemical suspected of causing cancer (carcinogens) or birth defects into water supplies. Some claim it will also require warning labels on everything that might cause cancer. A day of esoteric science and incomprehensible jargon was predicted. But Bruce Ames, Chairman of the Department of Biochemistry at the University of California at Berkeley, had plans to liven the proceedings. Walking into the room, Ames looked like the quintessential scientist: wire-rimmed bifocals, rumpled suit, tousled hair and a sallow complexion that showed he spent more time in his laboratory than in the California sunshine. As someone intoned about the mechanisms of carcinogenesis, Ames began to interject his own views. "The whole world is chock—full of carcinogens," Ames declared. "A beer, with its 700 parts per billion of formaldehyde and five parts per 100 of alcohol is a thousand times more hazardous than anything in the water. If you have beer on your breath, does that mean you have to warn everyone who comes within ten feet of you?" In an era when headlines shout about the latest cancer scare, Ames has a different message: the levels of most man-made carcinogens are generally so low that any danger is trivial compared with the levels of natural carcinogens. Ames is not a quack. At age 59, he is one of the nation's most respected authorities on carcinogenesis. But Ames slaughters sacred cows. He's taking on the environmental movement, which some have called the single most important social movement of the 20th century. Based on animal tests of nearly 1000 chemicals, the data show that daily consumption of the average peanut-butter sandwich, which contains traces of aflatoxin (a naturally occurring mold carcinogen in peanuts), is 100 times more dangerous than our daily intake of DDT from food, and that a glass of the most polluted well water in the Silicon Valley is 1000 times less of cancer risk than a glass of wine or beer is. He's not advising people to stop consuming peanut-butter, beer and wine. What he's saying is that most cancer risks created by man are trivial compared with everyday natural risks, and it's not clear how many of these are real risks. Both types distract attention from such enormous risk factors as tobacco.(A) [■] Ames's cancer research began about 25 years ago over a bag of potato chips.(B) [■] It struck him that no one knew what each chemical did to human genes, and there was no easy way to find out.(C) [■] At that time, scientists testing for carcinogenicity had to set up time-consuming and costly lab experiments on rats and mice.(D) [■] Armed with the knowledge that bacteria are sensitive to substances that cause mutation, and that carcinogens were likely to be mutagens, Ames developed a carcinogen test using bacteria. The Ames test was hailed as a major scientific development and is now used worldwide. One day in 1974, Ames, now teaching at Berkeley, suggested that some students test various household products. To his surprise, many common hair dyes tested positive, as did a flame retardant used in children's pajamas. Almost overnight, Ames became a hero of environmentalists when his findings led to new regulations and bans on certain chemicals. For the next decade public concern over carcinogens continued to rise. In fact, about half of all chemicals tested by Ames—both natural and man-made—turned out to be potentially carcinogenic when given in enormous dose to rats and mice. Ames at first assumed he had erred with his test. He hadn't. His error had been making the common, but naive, assumption that only man-made chemicals could be dangerous. "Why assume nature is benign?" he now says. The campaign supporting California's Proposition 65 convinced Ames that he had a duty to explain this to the public. Some people assume Ames is a stooge for the chemical industry, which he is not. He does no consulting for the chemical, drug or food companies, or for law firms. And he accepted no grants from business. Environmentalists reject Ames's arguments, saying that we are obligated to keep the total exposure to carcinogens as low as possible. "Somehow he thinks there has to be a choice," says Carl Pope of the Sierra Club. "If we had to choose between TCE a suspected cancer-causing solvent in drinking water and public education on cigarette smoking, maybe he's right. But we don't have to make a choice. "

单选题Listening3"BiologyClass"

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