国产精品亚洲无码专区,色播亚洲精品网站

相關(guān)推薦

歷年職稱英語(yǔ)考試綜合B類閱讀訓(xùn)練

　　有些書(shū)可供一嘗，有些書(shū)可以吞下，有不多的幾部書(shū)則應(yīng)當(dāng)咀嚼消化;這就是說(shuō)，有些書(shū)只要讀讀他們的一部分就夠了，有些書(shū)可以全讀，但是不必過(guò)于細(xì)心地讀;還有不多的幾部書(shū)則應(yīng)當(dāng)全讀，勤讀，而且用心地讀。以下是小編為大家搜索整理的歷年職稱英語(yǔ)考試綜合B類閱讀訓(xùn)練，希望能給大家?guī)?lái)幫助!更多精彩內(nèi)容請(qǐng)及時(shí)關(guān)注我們應(yīng)屆畢業(yè)生考試網(wǎng)!

歷年職稱英語(yǔ)考試綜合B類閱讀訓(xùn)練

　　Clone Farm

　　Factory farming could soon enter a new era of mass production. Companies in the US are developing the technology needed to “clone” chickens on a massive scale. Once a chicken with desirable traits has been bred or genetically engineered, tens of thousands of eggs, which will hatch into identical copies, could roll off the production lines every hour. Billions of clones could be produced each year to supply chicken farms with birds that all grow at the same rate, have the same amount of meat and taste the same.

　　This, at least, is the vision of the US’s National Institute of Science and Technology, which has given Origen Therapeutics of Burlingame, California, and Embrex of North Carolina $4.7 million to help fund research. The prospect has alarmed animal welfare groups, who fear it could increase the suffering of farm birds.

　　That’s unlikely to put off the poultry industry, however, which wants disease-resistant birds that grow faster on less food. “Producers would like the same meat quantity but to use reduced inputs to get there,” says Mike Fitzgerald of Origen. To meet this demand, Origen aims to “create an animal that is effectively a clone”, he says. Normal cloning doesn’t work in birds because eggs can’t be removed and implanted. Instead, the company is trying to bulk-grow embryonic stem cells taken from fertilized eggs as soon as they’re laid. “The trick is to culture the cells without them starting to distinguish, so they remain pluripotent,” says Fitzgerald.

　　Using a long-established technique, these donor cells will then be injected into the embryo of a freshly laid, fertilized recipient egg, forming a chick that is a “chimera”. Strictly speaking a chimera isn’t a clone, because it contains cells from both donor and recipient. But Fitzgerald says it will be enough if, say, 95 percent of a chicken’s body develops from donor cells/ “In the poultry world, it doesn’t matter if it’s not 100 percent,” he says.

　　Another challenge for Origen is to scale up production. To do this, it has teamed up with Embrex, which produces machines that can inject vaccines into up to 50,000 eggs an hour. Embrex is now trying to modify the machines to locate the embryo and inject the cells into precisely the right spot without killing it.

　　In future, Origen imagines freezing stem cells from different strains of chicken. If orders come in for a particular strain, millions of eggs could be produced in months or even weeks. At present, maintaining all the varieties the market might call for is too expensive for breeders, and it takes years to bread enough chickens to produce the billions of eggs that farmers need.

　　41. Which statement is the best description of the new era of factory farming according to the first paragraph?

　　A. eggs are all genetically engineered.

　　B. thousands of eggs are produced every hour.

　　C. cloned chicken are bulk-produced with the same growth rate, weight and taste.

　　D. identical eggs can be hatched on the production lines.

　　42. Which institution has offered USD 4.7 million to fund the research?

　　A. The US’s National Institute of Science and Technology.

　　B. Origen Therapeutics of Burlingame, Carfornia.

　　C. Embrex of North Carolina

　　D. Animal welfare groups.

　　43. In the third paragraph, by saving “Producers would like the same meant quantity but to use reduced inputs to get there,” Mike Fitzgerald means that he wishes

　　A. chickens’ quality could be maintained but with less investment.

　　B. chickens’ taste could be improved but at less costs.

　　C. chickens’ growth rate could be quickened but with less inputs.

　　D. chickens’ could grow to the same weight but with less feed.

　　44. Which of the following statements about Origen and Embrex is correct according to the fifth paragraph?

　　A. Origen and embrex will jointly invent machines to increase production.

　　B. Origen wants to purchase an efficient donor cells injectin machine.

　　C. Origen has joined hands with exbrex in producing cell-injecting machines.

　　D. Origen is the leading company in producing embryo-locating machines.

　　45. The technology of freezing stem cells from different strains of chicken can do all the following EXCEPT that

　　A. farmers can order certain strains of chicken only.

　　B. Origen can supply all the strains of chicken the market might need.