[外语类试卷]大学英语四级模拟试卷769及答案与解析.doc
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1、大学英语四级模拟试卷 769及答案与解析 一、 Part I Writing (30 minutes) 1 For this part, you are allowed 30 minutes to write a short essay on the topic of How to Become an Environment-friendly Visitor. You should write at least 120 words following the outline given below. 1许多人在旅游的同时对环境造成了一定程度的破坏 2提出一些措施减少对环境的破坏 3说明你个人是
2、如何做的 How to Become an Environment-friendly Visitor 二、 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 attached to the passage. For questions 1-7, mark: Y (for YES) if the sta
3、tement agrees with the information given in the passage; N (for NO) if the statement contradicts the information given in the passage; NG (for NOT GIVEN) if the information is not given in the passage. 1 How Ice Cream Works The U.S. ice cream industry sells about a million gallons of ice cream each
4、year, dispensing cones, gallons, pints, sundaes and other desserts through grocery stores and ice cream shops. In fact, eight percent of all the milk produced in the U.S. ends up in a frozen dairy product. Ice Cream or Frozen Dessert? Not just any frozen treat can be called ice cream. In fact, the U
5、.S. Department of Agriculture has specific tales that define what can and cant be labeled “ice cream“. To bear the “Meets USDA Ingredient Standard for Ice Cream“ stamp, it has to contain at least 10 percent milk fat, and a minimum of six percent non-fat milk solids. A gallon has to weigh at least 4.
6、5 pounds. The range of milk fat (sometimes referred to as butter fat) used in ice cream can go from the minimum 10 percent to a maximum of about 16 percent. Most premium ice creams use 14 percent milk fat. Higher fat content leads to better, richer taste and a creamier texture. Ice cream makers dont
7、 go higher than 16 percent because it would be costly and very high in calories. An ice cream with this much milk fat would also taste so rich that people would probably eat it in smaller amounts, which would be bad news for people who sell ice cream for a living. Other frozen desserts, such as sorb
8、ets (果汁冰糕 ), low-fat ice cream, and frozen yogurt, are not technically ice cream at all. Frozen custard is ice cream that has at least 1.4 percent egg yolk solids, and “soft serve“ can be any frozen milk-based dessert that has net gone through the hardening process-more on that later. In terms of sp
9、ecific ingredients, the recipe for ice cream is simple. But in scientific terms, its complicated stuff, lee cream is a colloid, a type of emulsion(乳状液 ). An emulsion is a combination of two substances that dont normally mix together. Instead, one of the substances is dispersed throughout the other.
10、In ice cream, molecules of fat are suspended in a water-sugar-ice structure along with air bubbles. The presence of air means that ice cream is also technically a foam. In addition to milk fat, non-fat milk solids, sugar, and air, ice cream also contains stabilizers and emulsifiers. Stabilizers help
11、 hold the air bubble structure together and give the ice cream a better texture. Although gelatin(凝胶 ) was originally used as a stabilizer, xanthan gum, guar gum, and other compounds are used today. Emulsifiers keep the ice cream smooth and aid the distribution of the fat molecules throughout the co
12、lloid. Egg yolks were once used, but ice cream manufacturers now tend to use other chemical compounds. These stabilizers and emulsifiers make up a very small proportion (less than one percent) of the ice cream. Making Ice Cream Whether its being made in your kitchen with a hand crank, at a local hom
13、emade ice cream shop with a stand-alone ice cream maker, or in a factory that cranks out thousands of gallons of ice cream every day, the process of making ice cream is basically the same. The only difference is the scale of the operation. First, you need ice cream mix. You can buy commercially made
14、 ice cream mix that is set to a certain milk fat content, lee cream factories usually make their own mix by combining milk, cream and sugar in a 3,000 gallon vat with the proportions and mixing controlled by computers. The mix is then pasteurized (用巴氏法灭菌 ), Or heated, to kill any harmful bacteria. I
15、f you were to make your own mix at home, you could pasteurize it by cooking it in a double boiler, or use an egg substitute or pasteurized egg product. This step is important, because otherwise people who eat your homemade ice cream could get sick due to salmonella contamination. According to the Ce
16、nters for Disease Control, those most at risk include the elderly, very young children, and people with compromised immune systems. The next step in production is adding flavor to the mix. There are thousands of varieties of ice cream, so just about any combination of flavors is possible. From vanil
17、la to cinnamon, chocolate to triple chocolate fudge brownie, it all gets blended into the ice cream mix. Ina factory, this step takes place in vats that hold hundreds of gallons of ice cream, while giant steel paddles do the mixing. In your kitchen, a large bowl and a food mixer will work, or even a
18、 wooden spoon and muscle power if you want some exercise. Solid chunks such as pieces of fruit, chocolate chunks, marshmallows, and candy are added later. The next step is where an ice cream making machine comes into play. The mix has to be simultaneously frozen and whipped. In a factory, this happe
19、ns in a giant tube surrounded by pipes. The pipes contain chemicals such as ammonia that freeze the tube, but the ammonia never comes into contact with the ice cream. The ice cream mix is pumped through the tube, where it gets cold very quickly. A dasher, or blade, turns inside the tube. This whips
20、the mixture, introducing the air bubbles that help give ice cream its structure. The dasher also scrapes the sides of the tube, clearing off ice crystals that form there. This prevents large ice crystals from mining the flavor and texture of the ice cream. All the elements of this process are carefu
21、lly monitored and controlled by computers. Most homemade ice cream shops use a batch freezer for this step, where the same process happens on a smaller scale. This step can be accomplished at home with a rock salt/ice mixture for freezing and a hand or electric cranked dasher to mix and scrape off t
22、he ice crystals. Once the ice cream has come out of the ice cream maker, the process isnt finished. At this point, the mixture is frozen, but still soft. Large chunks of candy and other goodies are now added. Then the ice cream is placed into containers. Factory machines pour it straight into carton
23、s or buckets, or it can be extruded (挤压出 ) into shapes that have wooden sticks placed into them for individual treats. Now the ice cream needs to be reduced to a very low temperature, zero degrees Fahrenheit or below. Factories make it even colder since they need the ice cream to stay frozen while i
24、t is packaged and loaded onto trucks. It needs to be very cold to freeze the ice cream quickly and prevent the formation of large ice crystals. This process is known as hardening. “Soft-serve“ is often simply ice cream that has not gone through this process. Well learn about the ice cream industry i
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- 外语类 试卷 大学 英语四 模拟 769 答案 解析 DOC
