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《中国药典》(2010年版)中亚硝酸钠滴定法采用哪种方法指示终点（ ）
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Farm animals provide man with food and material for clothing, leather and other products. Some, such as horses and oxen, provide transportation and power to pull machinery. Livestock gaze on about 40 percent of the United States land area.Cattle provide meat, hides and dairy products. Beef and dairy cattle account for about a third of all farm income in the U.S. Farms in the Midwest and sprawling ranches in the West raise most of the country’s beef cattle. The main Dairy’ Belt in the U. S. extends through the Northern states from New England to Minnesota. Eastern dairy farmers in Minnesota, Wisconsin and Iowa sell most of their milk to companies that make butter, cheese and evaporated milk.Hogs grow rapidly and provide meat and materials used to make many products. Hogs thrive on corn, and farmers in the Corn Belt of the Midwest raise more than two-third of U. S. hogs.Sheep and goats supply man with meat, wool and skins for leather. They are hardy animals that live well on poor grazing land.Poultry includes chickens, ducks, geese, turkeys and other birds raised for meat or eggs. Many farmers keep small flocks of chickens to supply their families with eggs and meat. But some U. S. farmers specialize in raising large flocks of meat or egg-laying chickens. They use scientific breeding and feeding methods.Some specialized farms raise mink and other animals for their fur, rabbits for meat, or silkworms for silk. Many farmers keep bees to get their honey and to help pollinate crops. Which animals in this passage are bred by scientific methods()
The crowd stirred and whispered in awe as, on the stage, the horse slowly tapped out the beat. Everyone became tense and quiet as the number of taps neared the correct answer to the horse trainer’s question. After The final tap, the horse paused, seemed to look around and stopped. The crowd went wild !The horse’s name was Clever Hans, the Educated Horse, and was featured in a vaudeville(杂耍) act in the early 1900s, in Europe. When asked a complicated mathematical question by his owner, Clever Hans would tap out the correct answer with his hooves. For example, if the answer was sixty- eight, Hans would tap out six with his left hoof and eight with his right hoof. Even mere remarkable, the owner would leave the room after asking the question, so there could be no secret signal between owner and horse. A mere animal seemed to be accomplishing a highly technical skill of man’s !It wasn’t until years later that the secret of the trick was revealed. The owner had trained Clever Hans to respond to slight signals. The horse became so sensitive that he learned when to stop from the crowd’s reaction. Members of the audience would start involuntarily, or give some unconscious signal, when Hans reached the right answer. Modern scientists now warn against the Clever Hans syndrome (综合征), whereby researchers unconsciously give clues to their animal subjects about the actions they like to see performed! The Clever Hans’s real talent was（）
The crowd stirred and whispered in awe as, on the stage, the horse slowly tapped out the beat. Everyone became tense and quiet as the number of taps neared the correct answer to the horse trainer’s question. After The final tap, the horse paused, seemed to look around and stopped. The crowd went wild !The horse’s name was Clever Hans, the Educated Horse, and was featured in a vaudeville(杂耍) act in the early 1900s, in Europe. When asked a complicated mathematical question by his owner, Clever Hans would tap out the correct answer with his hooves. For example, if the answer was sixty- eight, Hans would tap out six with his left hoof and eight with his right hoof. Even mere remarkable, the owner would leave the room after asking the question, so there could be no secret signal between owner and horse. A mere animal seemed to be accomplishing a highly technical skill of man’s !It wasn’t until years later that the secret of the trick was revealed. The owner had trained Clever Hans to respond to slight signals. The horse became so sensitive that he learned when to stop from the crowd’s reaction. Members of the audience would start involuntarily, or give some unconscious signal, when Hans reached the right answer. Modern scientists now warn against the Clever Hans syndrome (综合征), whereby researchers unconsciously give clues to their animal subjects about the actions they like to see performed! The first paragraph of this passage is （）
It takes a long time to grow a tree. How long Well, pine trees are the quickest growing trees, but still, they take twenty years to reach a size suitable for cutting and harvesting. An oak takes about sixty years to grow to a good size. A redwood may take hundreds of years.Lumber companies, which make their money on trees, depend on those that grow quickly. There- fore, they are always looking for methods to make trees grow faster. So far, the secret to fast growing trees seems to lie in "super-seeds." These are seeds that are gathered from the quickest growing trees in a forest. One company searched 100,000 acres of trees and selected the seeds from just fifteen trees. These two ounces of seed were enough to plant several hundred new trees. Eventually, when these trees have grown, seeds will again be taken only from the fastest growing trees of crop. This process of artificial selection will yield, in the future, a super-tree that will grow in half the time it takes normal trees to develop.Unfortunately, it takes a long time for a plan like this to reach its goal. The Weyerhauser Lumber Corporation, which started its first collection of seed in 1958, is just now beginning to harvest the super-seeds of the first generation of the faster growing trees. Super-trees ()
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