题目内容
计算机中常用的一种检错码是CRC，即 (11) 码。在进行编码过程中要使用 (12) 运算。假设使用的生成多项式是C(x)=x4+x3+x+1。原始报文为11001010101，则编码后的报文为 (13) 。CRC码 (14) 的说法是正确的。在无线电通信中采用7中取3定比码，它规定码字长为7位，并且其中总有且仅有3个“1”则编码效率为 (15) 。 12（）
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阅读下面这篇短文，短文后列出7个句子，请根据短文的内容对每个句子做出判断。如果该句提供的是正确信息，请选择A；如果该句提供的是错误信息，请选择B；如果该句的信息文章中没有提及，请选择C。 Imagine eating everything delicious your want--with none of the fat. That would be great, wouldn’t it New "fake fat" products appeared on store shelves in the United States recently, but not everyone is happy about it. Makers of the products, which contain a compound called olestra, say food manufacturers can now eliminate fat from certain foods. Critics, however, say the new compound can rob the body of essential vitamins and nutrients(营养物) and can also cause unpleasant side effects in some people. So it’s up to consumers to decide whether the new fatfree products taste good enough to keep eating. Chemists discovered olestra in the late 1960s, when they were searching for a fat that could be digested by infants more easily. Instead of finding the desired fat, the researchers created a fat the can’t be digested at all. Normally, special chemicals in the intestines(肠) "grab" molecules of regular fat and break them down so they can be used by the body. A molecule of regular fat is made up of three molecules of substances called fatty acids. The fatty acids are absorbed by the intestines and bring with them the essential vitamins A, D, E, and K. When fat molecules are present in the intestines with any of those vitamins, the vitamins attach to the molecules and are carried into the bloodstream. Olestra, which is made from six to eight molecules of fatty acids, is too large for the intestines to absorb. It just slides through the intestines without being broken down. Manufacturers say it’s that ability to slide unchanged through the intestines that makes olestra so valuable as a fat substitute. It provides consumers with the taste of regular fat without any bad effects on the body. But critics say olestra can prevent vitamins A, D, E, and K from being absorbed. It can also prevent the absorption of carotenoids(类胡萝卜素), compounds that may reduce the risk of cancer, heart disease, etc. Manufacturers are adding vitamins A, D, E, and K as well as carotenoids to their products now. Even so, some nutritionists are still concerned that people might eat unlimited amounts of food made with the fat substitute without worrying about how many calories they are consuming. Adding vitamins to olestra may trigger a new wave of fake food production.
阅读下面的短文，文中有15处空白，每处空白给出4个选项，请根据短文的内容从4个选项中选择1个最佳答案。 A satisfactory psychological theory must allow us to predict behavior. For instance, a satisfactory theory of hunger will allow us to predict when people will eat and not eat. A broadly satisfying, (51) theory should have a wide range of applicability. A broad theory of hunger might apply (52) human beings and lower animals, to normal weight and overweight people, and to people who have (53) of food for differing lengths of time. If our (54) cannot be adequately explained by or predicted from a given theory, we should consider revising or replacing that theory. In psychology many theories have been found to be (55) of explaining or predicting new observations. As a result they have been revised (56) .For example, the theory that hunger results from stomach contractions may be (57) correct for normal weight individuals, but it is inadequate as an (58) for feelings of hunger among the overweight. (59) theories also focus on biological variables, such as fat cells and brain (60) , and psychological variables such as the presence of other people who are eating and the time of day. The (61) of controlling behavior in psychology is highly (62) . Some people erroneously think that psychologists seek ways to make people do their bidding—like puppets dangling on strings. This is not so. Instead, psychologists help (63) change their behavior for their own benefit. Psychologists are (64) to belief in the dignity of human beings, and human dignity demands that people be free to make their own decisions and choose their own behavior. Psychologists are learning more all the time about the (65) influences on human behavior, but they apply this knowledge only upon request and in ways they believe will be helpful to an individual or an institution.
第三篇 If the salinity(含盐量) of ocean waters is analyzed, it is round to vary only slightly from place to place. Nevertheless, some of these small changes are important. There are three basic processes that cause a change in oceanic salinity. One of these is the subtraction of water from the ocean by means of evaporation—conversion of liquid water to water vapor. In this manner, the salinity is increased, since the sales stay behind. If this is carried to the extreme, of course, white crystals of salt would be left behind; this, by the way, is how much of the table salt we use is actually obtained. The opposite of evaporation is precipitation, such as rain, by which water is added to the ocean. Here the ocean is being diluted so that the salinity is decreased. This may occur in areas of high rainfall or in coastal regions where rivers flow into the ocean. Thus salinity may be increased by the subtraction of water by evaporation, or decreased by the addition of fresh water by precipitation or runoff. Normally, in tropical regions where the sun is very strong, the ocean salinity is somewhat higher than it is in other parts of the world where there is not as much evaporation. Similarly, in coastal regions where rivers dilute the sea, salinity is somewhat lower than in other oceanic areas. A third process by which salinity may be altered is associated with the formation and melting of sea ice. When seawater is frozen, the dissolved materials are left behind. In this manner, seawater directly beneath freshly formed sea ice has a higher salinity than it did before the ice appeared. Of course, when this ice melts, it will tend to decrease the salinity of the surrounding water. In the Weddell Sea, off Antarctica, the densest water in the oceans is formed as a result of this freezing process, which increases the salinity of cold water. This heavy water sinks and is found in the deeper portions of the oceans of the world. All of the following are processes that decrease salinity EXCEPT______.
阅读下面的短文，文中有15处空白，每处空白给出4个选项，请根据短文的内容从4个选项中选择1个最佳答案。 A satisfactory psychological theory must allow us to predict behavior. For instance, a satisfactory theory of hunger will allow us to predict when people will eat and not eat. A broadly satisfying, (51) theory should have a wide range of applicability. A broad theory of hunger might apply (52) human beings and lower animals, to normal weight and overweight people, and to people who have (53) of food for differing lengths of time. If our (54) cannot be adequately explained by or predicted from a given theory, we should consider revising or replacing that theory. In psychology many theories have been found to be (55) of explaining or predicting new observations. As a result they have been revised (56) .For example, the theory that hunger results from stomach contractions may be (57) correct for normal weight individuals, but it is inadequate as an (58) for feelings of hunger among the overweight. (59) theories also focus on biological variables, such as fat cells and brain (60) , and psychological variables such as the presence of other people who are eating and the time of day. The (61) of controlling behavior in psychology is highly (62) . Some people erroneously think that psychologists seek ways to make people do their bidding—like puppets dangling on strings. This is not so. Instead, psychologists help (63) change their behavior for their own benefit. Psychologists are (64) to belief in the dignity of human beings, and human dignity demands that people be free to make their own decisions and choose their own behavior. Psychologists are learning more all the time about the (65) influences on human behavior, but they apply this knowledge only upon request and in ways they believe will be helpful to an individual or an institution.
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