单选题Though Americans do not currently ______ abortions directly, costs are carried by other Americans through higher insurance premiums.

单选题It is agreed that all nations should take measures against terrorism on the basis of the UN ______ and other international laws.

单选题We all know that the normal human daily cycle of activity is of some 748 hours' sleep alternating with some 16417 hours' wakefulness and that, broadly speaking, the sleep normally coincides with the hours of darkness. Our present concern is with how easily and to what extent this cycle can be modified. The question is no mere academic one. The ease, for example, with which people can change from working in the day to working at night is a question of growing importance in industry where automation calls for round the-clock working of machines. It normally takes from five days to one week for a person to adapt to a reversed routine of sleep and wakefulness, sleeping during the day and working at night. Unfortunately, it is often the case in industry that shifts are changed every week: a person may work from 12 midnight to 8 a.m. one week, 8 a.m. to 4 p.m. the next, and 4 p. m. to 12 midnight the third and so on. This means that no sooner has he got used to one routine than he has to change to another, so that much of his time is spent neither working nor sleeping very efficiently. The only real solution appears to be to hand over the night shift to a number of permanent night workers. An interesting study of the domestic life and health of night shift workers was carried out by Brown in 1957. She found a high incidence of disturbed sleep find other disorders among those on alternating day and night shifts, but no abnormal occurrence of these phenomena among those on permanent night work. This latter system then appears to be the best long-term policy, but meanwhile something may be done to relieve the strains of alternate day and night work by selecting those people who can adapt most quickly to the Changes of routine. One way of knowing when a person has adapted is by measuring his body temperature. People engaged in normal day-time work will have a high temperature during the hours of wakefulness and a low one at night; when they change to night work the pattern will only adjust gradually back to match the new routine and the speed with which it does so parallels, broadly speaking, the adaptation of the body as a whole, particularly in terms of performance. Therefore, by taking body temperature at intervals of two hours throughout the period of wakefulness it can be seen how quickly a person can adapt to a reversed routine, and this could be used as a basis for selection. So far; however, such a form of selection does not seem to have been applied in practice.

单选题Whose works will be on show on Jan. 6 at China National Art Museum?

单选题Lincoln thought it was wrong to keep Negroes ______ slaves.

单选题 请选出下面划线部分读音不同的选项

单选题 Latino youths need better education for Arizona to take full advantage of the possibilities their exploding population offers. Arizona's fast-growing Latino population offers the state tremendous promise and a challenge. Even more than the aging of the baby boomers, the Latino boom is fundamentally reorienting the state's economic and social structure. Immigration and natural increase have added 600,000 young Latino residents to the state's population in the past decade. Half of the population younger than 18 in both Phoenix and Tucson is now Latino. Within 20 years, Latinos will make up half of the homegrown entry-level labour pool in the state's two largest labour markets. What is more, Hispanics are becoming key economic players. Most people don't notice it, but Latinos born in Arizona make up much of their immigrant parents' economic and educational deficits. For example, second-generation Mexican-Americans secure an average of 12 grades of schooling where their parents obtained less than nine. That means they erase 70 percent of their parents' lag behind third-generation non-Hispanic Whites in a single generation. All of this hands the state a golden opportunity. At a time when many states will struggle with labour shortages because of modest population growth, Arizona has a priceless chance to build a populous, hardworking and skilled workforce on which to base future prosperity. The problem is that Arizona and its Latino residents may not be able to seize this opportunity. Far too many of Ari zona's Latinos drop out of high school or fail to obtain the basic education needed for more advanced study. As a result, educational deficits are holding back many Latinos—and the state as well. To be sure, construction and low-end service jobs continue to absorb tens of thousands of Latino immigrants with little formal education. But over the long term, most of Arizona's Latino citizens remain ill-prepared to prosper in an increasingly demanding knowledge economy. For the reason, the educational uplift of Arizona's huge Latino population must move to the centre of the state's agenda. After all, the education deficits of Arizona's Latino population will severely cramp the fortunes of hardworking people if they go unaddressed and could well undercut the state's ability to compete in the new economy. At the entry level, slower growth rates may create more competition for low-skill jobs, displacing Latinos from a significant means of support. At the higher end, shortages of Latinos educationally ready to move up will make it that much harder for knowledge-based companies staff high-skill positions.

单选题 A useful definition of an air pollutant is a compound added directly or indirectly by humans to the atmosphere in such quantities as to affect humans, animals, vegetation, or material adversely. Air pollution requires a very flexible definition that permits continuous change. When the first air pollution laws were established in England in the fourteenth century, air pollutants were limited to compounds that could be seen or smelled—a far cry from the extensive list of harmful substances known today. As technology has developed and knowledge of the health aspects of various chemicals has increased, the list of air pollutants has lengthened. In the future, even water vapour might be considered an air pollutant under certain conditions. Many of the more important air pollutants, such as sulphur oxides, carbon monoxide, and nitrogen oxides, are found in nature. As the earth developed, the concentrations of these pollutants were altered by various chemical reactions; they became components in biogeochemical cycles. These reactions serve as an air purification scheme by allowing the compounds to move from the air to the water or soil. On a global basis, nature's output of these compounds dwarfs that resulting from human activities. However, human production usually occurs in a localized area, such as a city. In this localized region, human output may be dominant and may temporarily overload the natural purification scheme of the cycles. The result is an increased concentration of noxious chemicals in the air. The concentrations at which the adverse effects appear will be greater than the concentrations that the pollutants would have in the absence of human activities. The actual concentration need not be large for a substance to be a pollutant; in fact the numerical value tells us little until we know how much of an increase this represents over the concentration that would occur naturally in the area. For example, sulphur dioxide has detectable health effects at 0.08 parts per million (ppm), which is about 400 times its natural level. Carbon monoxide, however, has a natural level of 0.1ppm and is not usually a pollutant until its level reaches about 15ppm.

单选题The response to our financial appeal______anything we expected.

单选题The {{U}}rigor{{/U}} of the winter in Russia was often described by Mogol.

单选题Since Dick was busy, he rarely had time to go to the cinema; ______.

单选题At first Jackie prayed, frozen in fear, but gradually his terror ______ curiosity.

单选题Looking back on my childhood, I am convinced that naturalists are born and not made. Although we were all brought up in the same way, my brothers and sisters soon 27 their pressed flowers and insects. Unlike them, I had no ear for music and languages. I was not an 28 reader and I could not do mental arithmetic. Before World War I we spent our summer holidays in Hungary. I have only the 29 memory of the house we lived in and of my room and my toys. But I do have a crystal-clear memory of the dogs, the farm animals, the local birds, and above all, the insects. I am a naturalist, not a scientist. I have a strong love of the natural world and my 30 had led me into varied investigations. I love discussing my 31 topics and enjoy burning the midnight oil while reading about other people's observations and 32 Then something happens that brings these observations together in my conscious mind. Suddenly you fancy you see the answer to the riddle, because it all seems to fit 33 together. This has resulted in my publishing 300 papers and books, which some might 34 with the title of scientific research. But curiosity, a keen eye, a good memory and enjoyment of the animal and plant world do not make a scientist. A scientist requires not only 35 but hard training, determination and a goal. A scientist, up to a point, can be made. A naturalist is born. If you can 36 the two, you get the best of both worlds. A. combine B. connect C. serf-discipline D. enthusiasm E. regulations F. discoveries G. dim H. eventually I. abandoned J. honor K. disposed L. modest M. favorite N. early O. perfectly

单选题Thank you for applying for a position with our firm. We do not have any openings at this time, but we shall keep your application on ______ for two months.

单选题The President______his deputy to act for him while he was abroad.

单选题The manager was very pleased with the increased ______ from the factory last month.

单选题They are seeking to ______ the most advanced technological levels in the world.

单选题Many troubles ______ from this misunderstanding.

单选题Insomnia, or “poor sleep”, can have bad effects on a persons health and general well-being. It can_____21on both our physical and mental health and can lead to other health_____22. Insomnia can b