(1)One important outcome of the work on the expression of genes in developing embryos is sure to be knowledge that can help preventing birth defects. Just as promising (26) is the possibility of unraveling the complicated writing (27) of the brain. A mechanic gets valuable insight how an (28) automobile works by rebuilding car engines; similarly, neuroscientists can learn how the brain functions from (29) the way it is put together. The next step pursuing the (30) goal is to find out how the blueprint genes, the home box genes, control the expression of other genes that create the valves and piston of the working cerebral engine. The protein encoded by the latter genes could change the (31) stickiness of the cell surface, the shape of the cell or its metabolism to create the characteristic peculiar to, say, neurons or neural-crest cell. Surface proteins may be the (32) mechanism, whereby similar programmed cells stick together to form specific structures; they might also n (33) the local environment to help the cell decide what is to do. Clarifying tho mechanisms will engage the best talents in (34) embryology and molecular biology for some times to come. (35) What is perhaps the most intriguing question of all is if the brain is powerful enough to solve the puzzle of its own creation.
kollie
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(2)Vitamins, like minerals, are chemicals. There is absolutely not difference in the chemical structure (26) of the nature vitamin C and the chemical structure (27) of the synthetic vitamin C. Also, while most sub- stances are harmless at very low level of intake, all (28) substance -- even the elements that are esntial to life -- can be dangerous if you overdo them. Take water for example. Six or eight glass a day will keep your body in good fluid balance. But you can also be drown (29) in it. Some people argue that individuals vary greatly (30) in their need for nutrients, it cannot necessarily be stated any given amount is too much; that is all (31) relative. But since there is little solid information on what is the optimal intake of any esntial nutrient in healthy individuals, it would be impossible to give guidelines that take the proportional needs into the (32) account. Just as with other drugs, the relation to (33) different vitamin dosages varies, with some people better able than others to tolerate large amounts. While we do know that very specifically what the toxic level (34) is for vitamins A and D, we are far less sure about vitamin E, even though it, too, is fat-soluble, and we still don’t understand the water-soluble vitamin, the C (35) and the B groups, which the body cant store.
hvs
cousin的音标(3)The telephone system is a circuit-switched network. For much of the history of the system, when you placed (26) a call, you were renting a pair of copper wires that ran continuously from your telephone to the other party’s phone. You had excluding u of tho wires during the (27) call; when you hung up, they were rented to someone el. Today the transaction is more complicated. ( your call may well posss a fiber-optic cable or a satellite with hundreds of other calls), but more conceptually the system (28) still works the same way. When you dial the phone, you get a private connection of one other party. This is an alternative network architecture called (29) packet switching, in which all stations are always connected to the network, but they receive only the messages addresd to them. It is as if your telephone was always tuned in to (30) thousands of conversations going on the wire, but you (31) heard only the occasional word intended to you. Most (32) computer networks employ packet switching, becau it is more efficient than circuit switching when traffic is heavy. It ems reasonable the existing packet-switched (33) network will grow, and new one may be created; they could (34) well absorb traffic that would otherwi go to the telephone system and thereby reduce the need for telephone numbers. (35)
瓜瓜龙英语toast是什么意思(4) The German poet and polymath Johann Wolfgang von Goethe pondered the question of how organisms develop in his scientific studies of form and structure immature plants and animals, a field he found and named morphology. His arch for a single basic body plan (26) across all life-forms led him to think about the prevalence of repeating (27) gments in body structures. The spinal columns of fish, reptiles, (28) birds and mammals, for instance, all are made of long strings of (29) repeated vertebrae. Among invertebrates the growth of virtually identical gments is how striking: in earthworms, for example, even (30) internal organs are repeated in rial gments. Likewi, the abdomen of flies and other incts are gmented, as are the (31) successive wormlike articulations in crabs, shrimps and other crustaceans. To Goethe the evidence suggested that nature takes a building-block approach to generate life, repeating a basic element (32) again and again to arrive at a complicated organism. The only glaring (33) hole he could e in the theory was the apparent lack of sort of (34) gmentation in the vertebrate heads. In 1790 he hypothesized that (35) spinal vertebrate is modified during the development to form the skull.
暑期初中家教多少钱
(5)Literature is a means by which we know ourlves. By it we (26) meet future lves, and recognize past lves; against it we match our prent lf. Its primary function is to validate and re-create the lf in all its individuality and distinctness. In doing so, it cements a n of relationship between the lf and the otherness of the book, and allows us a notion of ourlves as sociable. Its shared knowledge is vicarious experience; by this means we enlarge our understandings (27) of what it means to be human, of the corporate and independent (28) nature of human society. The act of reading the book marks both our difference in and our place in the human fabric. The more we read, (29) the more we are. In the act of reading silently we are alone from the (30) book, parate from ones own immediate surroundings. Yet in the (31) act of reading we enter other minds and other places, enlarge our (32) dialogue with the world. Thus paradoxically, while dingaging from the immediate we are increasing its scope. In silence, reading activates a deeply creative function of consciousness. We are deeply committed to the narrative which we coexist while engaged in (33) reading. All kinds of prent physical discomfortness may be (34) unnoticed while we are reading, and actual time is replaced
by narrative time. To imaginatively enter a fictional world by reading it (35) is then both a liberation from lf and an expansion of lf.
bazi
