题目内容
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A.it must be raining
B.it must rain
C.it must have rained
D.it must have been rained
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A.set back
B.held up
C.stood back
D.kept down
Every year thousands of lives （) in road accidents because of careless driving.
A.lose
B.lost
C.have lost
D.are lost
A、consideration
B、inquiry
C、regard
D、application
A.way
B.road
C.journey
D.trip
A.Derivation
B.Conversion
C.Backformation
D.Blending
1. “The Nobel Prize in Physiology or Medicine 2004”Press Release(15分)
4 October 2004
The Nobel Assemblyat Karolinska Institutet has today decided to award The Nobel Prize in Physiology or Medicine for 2004 jointly toRichard Axel and Linda B. Buckfor their discoveries of "odorant receptors and the organization of the olfactory system"
Summary
The sense of smell long remained the most enigmatic of our senses. The basic principles for recognizing and remembering about 10,000 different odours were not understood. This year's Nobel Laureates in Physiology or Medicine have solved this problem and in a series of pioneering studies clarified how our olfactory system works. They discovered a large gene family, comprised of some 1,000 different genes (three per cent of our genes) that give rise to an equivalent number of olfactory receptor types. These receptors are located on the olfactory receptor cells, which occupy a small area in the upper part of the nasal epithelium and detect the inhaled odorant molecules.
Each olfactory receptor cell possesses only one type of odorant receptor, and each receptor can detect a limited number of odorant substances. Our olfactory receptor cells are therefore highly specialized for a few odours. The cells send thin nerve processes directly to distinct micro domains, glomeruli, in the olfactory bulb, the primary olfactory area of the brain. Receptor cells carrying the same type of receptor send their nerve processes to the same glomerulus. From these micro domains in the olfactory bulb the information is relayed further to other parts of the brain, where the information from several olfactory receptors is combined, forming a pattern. Therefore, we can consciously experience the smell of a lilac flower in the spring and recall this olfactory memory at other times.
Richard Axel, New York, USA, and Linda Buck, Seattle, USA, published the fundamental paper jointly in 1991, in which they described the very large family of about one thousand genes for odorant receptors. Axel and Buck have since worked independent of each other, and they have in several elegant, often parallel, studies clarified the olfactory system, from the molecular level to the organization of the cells.
B.had been teaching, since
C.would teach, for
D.has been teaching, for
