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1、课时跟踪练(一) Welcome to the unit & Reading.阅读理解APlant cloning has been an agricultural technique used by farmers and gardeners for centuries. Grafting (嫁接) is a common form of plant cloning. Many plants in nature actually clone themselves and reproduce asexually.Cloned plants are much more predictable t
2、han normal plants, so their yield (产量) is more reliable. Cloned plants also reproduce faster, limiting the amount of time between planting and harvesting. It is also often cheaper to produce seeds through cloning than through traditional methods. Plants can essentially be optimized so that farmers o
3、r individual growers always have the best seeds available. With more yield at a faster rate, farms can produce more food for more people while decreasing overall costs.Cloning can be used to wipe out diseases that previously killed off entire fields of crops. This would make plants immune (免疫的) to t
4、he kinds of diseases that farmers and gardeners around the world fear each year. Crop failures due to disease and virus could become a thing of the past. Also, plants that are near extinction can be brought back to life through cloning.Through cloning scientists can develop “super” fruits and vegeta
5、bles of superior nutritional quality. This could make for a healthier population overall. This is already being done through selective pollination (授粉), and genetic cloning could take it to the next level.By plant cloning we have a population of identical plants and all these plants equally suffer f
6、rom the same diseases, but in nature the weak would die and the strong would survive. While there are some dangers to consider with plant cloning, there are plenty of benefits that could prove vital to the propagation (繁衍) of the human species.语篇解读：本文主要讲了克隆植物的好处：增加农作物产量、提高植物的免疫力、提高水果和蔬菜的质量等。1The und
7、erlined word “optimized” in Paragraph 2 can be replaced by “ ”AenlargedBproducedCperfected Dexamined解析：选C词义猜测题。根据第二段中该词的下文“growers always have the best seeds available”种植者可以有最好的种子使用可猜测该词意为“好的或优的”。2According to the text, cloned plants .Ahave lower yield than normal plantsBhave a short growth cycle Cr
8、esist various kinds of diseasesDneed little care from people 解析：选B推理判断题。根据第二段第二句可知，克隆植物繁殖快，从种植到收获，间隔时间短，也就是生长周期短。3What can we infer from the text?AThe fruits produced by cloned plants taste much better.BThere are more cloned plants than normal plants.CPlant cloning can disturb the laws of nature.DPe
9、ople should avoid eating cloned fruits.解析：选C推理判断题。根据最后一段可知，克隆植物会造出完全一样的植物，它们也可能会患上同样的病。这与自然中适者生存的法则是相反的。所以说克隆植物可以打破自然法则。4What is the main purpose of the text?ATo warn the negative effects of plant cloning.BTo present different kinds of plant cloning.CTo predict the future of plant cloning.DTo inform
10、 us about the advantages of plant cloning.解析：选D写作意图题。根据各段的段首句可知，本文主要讲的克隆植物的好处：增加农作物的产量、提高植物的免疫力、提高水果和蔬菜的质量和利于人类的繁衍等。B With an eye for style and a heart for the environment, 18yearold Alexis Giger launched a doityourself blog aimed at “reducing your environmental impact fashionably”The idea was spark
11、ed (激发) by the ecology unit in her biology class at Charlotte Latin School last year, she said, which taught her about issues like deforestation and habitat destruction.“I started thinking about what I could do to stop the wastefulness in my immediate community，” the fashion lover said. “The blog, ,
12、 aims to make reusing secondhand goods store finds or last seasons pieces easy and fashionable while cutting down on the resources consumed by garment production，” Alexis said. Through online research, she discovered that a simple cotton Tshirt takes more than 700 gallons of water to make. “It made
13、me realize that the fashion industry consumes huge amounts of natural resources as it relies on producing garments quickly and in large supply many of the garments are only intended to be worn three or four times，” she said. Alexis had a number of tools to help her get started. Her mom, Kimberly, ta
14、ught her to sew when she was 5. Her grandmother taught her to crochet (钩边) around the same time. Alexis said she also gained technical knowledge and inspiration from her parttime job at a clothing company that creates theater wardrobes for schools and drama productions.Prior to the blog launch, she
15、spent several months illustrating “recycling” projects by creating photo tutorials. Though Ecouturier hasnt been online long, shes been getting positive feedback.“Ive had people come up to me in the hall and say，Hey, I saw your blog. Im working on one of the projects right now，” Alexis said.She said
16、 she hasnt bought a brandnew piece of clothing since last July, and her thrift store shopping has paid off with finds such as a $5 (31 yuan) dress she wore to homecoming.“Taking an hour from Saturday afternoon to make something for yourself can really have an impact on the environment. A little change every day can
