【正文】 39。 however, some are under consideration for release. For example, GM salmon, capable of growing almost 30 times faster than natural salmon, may soon be approved by the FDA (Food and Drug Administration) in the . for release into open waters without a single study on the impact on human health or the environment. Risks: the other side of the debate Environmental damage The problem with GM crops is that there is little known about what effect they will have in, say, 20 years time. The geic structure of any living anism is plex and GM crop tests focus on shortterm effects. Not all the effects of introducing a foreign gene into the plex geic structure of an anism are tested. Will the pests that a crop was created to resist eventually bee resistant to this crop? Then there is always the possibility that we may not be able to destroy GM crops once they spread into the environment. Risk to food web. A further plication is that the pesticide produced in the crop may unintentionally harm creatures. GM crops may also pose a health risk to native animals that eat them. The animals may be poisoned by the builtin pesticides. Tests in the . showed that 44% of caterpillars (毛蟲 ) of the monarch butterfly died when fed large amounts of pollen(花粉 )from GM corn. Disease. Another concern is disease. Since some crops are modified using the DNA from viruses and bacteria, will we see new diseases emerge? What about the GM crops that have antibioticresistant marker genes? Marker genes are used by scientists to determine whether their geic modification of a plant was successful. Will these antibioticresistant genes be transferred to microanisms that cause disease? We already have a problem with ineffective antibiotics. How can we develop new drugs to fight these new bugs? Until further studies can show that GM foods and crops do not pose serious threats to human health or the world39。 The Decrease of Public Transportation Ticket Fare Part Ⅱ Reading Comprehension (Skimming and Scanning)(15 minutes) Directions: In this part, you will have 15 minutes to go over the passage quickly and answer the questions on Answer Sheet 1. For questions 17,choose the best answer from the four choices marked A), B), C) and D). For questions 810,plete the sentences with the information given in the passage. The Debate Over Geically Modified Foods For thousands of years farmers have used a process of selection and cross breeding to continually improve the quality of crops. Traditional breeding methods are slow, requiring intensive labor: while trying to get a desirable trait in a bred species, undesirable traits will appear and farmers must continue the process over and over again until all the undesirables are bred out. In contrast, anisms acquire one specific gene or a few genes together through geic modification, without other traits included and within a single generation. However, this technology too is inherently unpredictable and some scientists believe it can produce potentially dangerous results unless better testing methods are developed. Traditional breeding is based on sexual reproduction between like anisms. The transferred genes are similar to genes in the cell they join. They are conveyed in plete groups and in a fixed sequence that harmonizes with the sequence of genes in the partner cell. In contrast, bioengineers isolate a gene from one type of anism and collect it randomly into the DNA of a dissimilar species, disrupting its natural sequence. One of the main differences between conventional and geically modified crops is that the former involves crosses either within species or between very closely related species. However, GM crops can have genes from closely related species or even from bacteria and viruses. Benefits: one side of the debate Economical? GM supporters tell farmers that they stand to reap enormous profits from growing GM crops. It takes a shorter time to produce the desired product. It is precise and there are no unwanted genes. To produce the GM crops, modern biotechnology is used which requires highly skilled people and sophisticated and expensive equipment. Large panies need considerable investments in laboratories, equipment and human resources, hence the reason why GM crops are more expensive for farmers than traditional crops. Herbicideresistant crops So what other 考試吧 ()第一個(gè)極力推崇人性化服務(wù)的專業(yè)考試培訓(xùn)網(wǎng)站 ！ 提供歷年試題，模擬試題，模擬盤，教程，專業(yè)課試題下載，考試培訓(xùn)等。 2. 此措施帶來的好處 。 考試吧 ()第一個(gè)極力推崇人性化服務(wù)的專業(yè)考試培訓(xùn)網(wǎng)站 ！ 提供歷年試題，模擬試題，模擬盤，教程，專業(yè)課試題下載，考試培訓(xùn)等。 每日更新 !!! 考試吧論壇： 考試吧博客： 考試吧商城： Part Ⅰ Writing (30 minutes) Directions: For this part, you are allowed 30 minutes to write a short essay entitled The Decrease of Public Transportation Ticket Fare. You should write at least 120 words following the outline given below: 1. 近來一些城市政府實(shí)施多 項(xiàng)舉措降低公共交通票價(jià)，大力發(fā)展公共交通 。 3. 作為市民應(yīng)如何響應(yīng)政府的號(hào)召。 每日更新 !!! 考試吧論壇： 考試吧博客： 考試吧商城： advantages do GM crops hold for farmers? GM crops can be produced to be herbicide (除草劑 ) resistant. This means that farmers could spray these crops with herbicide and kill the weeds, without affecting the crop. In effect, the amount of herbicide used in one season would be reduced, with a subsequent reduction in costs for farmers and consumers. Biotechnology panies are even experimenting with crops that can be geically modified to be drought and salttolerant, or less reliant on fertilizer, opening up new areas to be farmed and leading to increased productivity. However, the claims of less herbicide usage with GM crops have till now not been independently supported by facts. Better quality foods Even animals can be geically modified to be leaner, grow faster, and need less food. They could be modified to have special characteristics, such as greater milk production in cows. These modifications again lead to improved productivity for farmers and finally lo