本文为正在紧张复习英语四级的同学准备了一篇英语,希望大家多加练习。
The food irradiation process is a simple one. The new U.S. plant, Vindicator of Florida Incorporated in Mulberry, Fla., uses a material called cobalt 60 to irradiate food. Cobalt 60 is radioactive isotope of the metallic element cobalt. Cobalt 60, which gives off radiation in the form of gamma rays, is also used for radiation therapy for cancer patients and for sterilizing hospital equipment. The radioactive isotope is created by bombarding cobalt with subatomic particles in a nuclear reactor. However, irradiation plants do not themselves contain nuclear reactors.
In the irradiation plant, food is exposed to thin rods of cobalt 60. The rods give off gamma rays, which disrupt chemical processes in contaminating organisms. The disruption breaks down the cell walls of organisms or destroys their genetic material. The dose, set by the U.S. Food and Drug Administration , is enough to kill organisms on food, but not enough to produce significant changes in the food itself.
Although irradiation slightly decreases the nutritive value of foods, the loss is less than that produced by some other methods of food preservation. Canning, for example, results in a much greater loss of nutrients.
Those who object to irradiation say that the process may create substances not found in nonirradiated food. Since the 1960s researchers have studied irradiated food at microscopic levels to try to find such substances, called unique radiolytic products. After reviewing these studies, the FDA determined that compounds formed during irradiation are similar to substance found in nonirradiated foods and are not dangerous to consume.
Destruction of microorganisms that cause illness is an important goal of irradiation. About 250 million cases of food poisoning or 1 per personoccur every year in the U.S., according to FDA estimates. Food poisoning can cause vomiting, diarrhea, fever, headacheand, occasionally, death.
Because of the apparent safety of food irradiation, and the problems presented by contaminated food, scientific groupsincluding the American Medical Association, the World Health Organization, and the United Nations food and Agriculture Associationhave voiced nearly universal support for the process. Worldwide, 38 nations have approved irradiation for 355 products.
Like microwave ovens, food irradiation has aroused apprehension and misunderstanding. Yet it has been scrutinized more thoroughly than other methods of food treatment that we have come to regard as safe, and it appears to be a method whose time has come.
1.Cobalt 60, besides irradiating food, is also employed to ___.
A.detect metallic flaws
B.run a nuclear reactor
C.cure cancer patients
D.strengthen concrete walls
2.Gamma rays used to irradiate food ___.
A.are generally not strong enough to destroy contaminating organisms
B.do not bring about significant changes in the food itself
C.may destroy some of the nutrients in the food
D.should be submitted to FDA for approval
3.Irradiated food ___.
A.certainly loses its nutritive value
B.maintains its nutritive value no different from the nonirradiated
C.keeps its nutritive value better than canned food
D.is recommended as the best of all preserved foods
4.With cases of food poisoning increasing, ___.
A.food irradiation should be carried out with care
B.it is more urgent to irradiate foods
C.medical researches into treatment of the diseased should be strengthened
D.Americans are beginning to accept food irradiation
5.The passage may be taken from ___.
A.a news report
B.a textbook of food processing
C.a book of popular science
D.a manual of food irradiation
答案:CBCCD
人教版六年级上册英语第四单元综合评价课时特训答案
人教版六年级上册英语Unit 5 Period 1课时特训答案
人教版七年级上册英语Unit 1第一课时课时特训答案
人教版七年级上册英语Unit 4第一课时课时特训答案
人教版七年级上册英语Unit 2第二课时课时特训答案
人教版六年级上册英语Unit 5 Period 5课时特训答案
人教版七年级上册英语Unit 3第一课时课时特训答案
人教版七年级上册英语Starter Unit 1第一课时课时特训答案
人教版六年级上册英语Unit 6 Period 6课时特训答案
人教版六年级上册英语Recycle 2 Period 3课时特训答案
人教版六年级上册英语Unit 5 Period 3课时特训答案
人教版六年级上册英语Unit 5 Period 4课时特训答案
人教版六年级上册英语Unit 6 Period 1课时特训答案
人教版六年级上册英语Unit 6 Period 3课时特训答案
人教版七年级上册英语Unit 6第二课时课时特训答案
人教版七年级上册英语Unit 4第四课时课时特训答案
人教版七年级上册英语Unit 5第三课时课时特训答案
人教版六年级上册英语Unit 5 Period 2课时特训答案
人教版六年级上册英语期末综合测试卷一课时特训答案
人教版六年级上册英语Unit 6 Period 2课时特训答案
人教版七年级上册英语Unit 4第三课时课时特训答案
人教版七年级上册英语Unit 3单元自测课时特训答案
人教版七年级上册英语Unit 3第二课时课时特训答案
人教版七年级上册英语Unit 4单元自测课时特训答案
人教版七年级上册英语Unit 5第四课时课时特训答案
人教版六年级上册英语Recycle 2 Period 1课时特训答案
人教版七年级上册英语Starter Unit 1第二课时课时特训答案
人教版六年级上册英语第六单元综合评价课时特训答案
人教版七年级上册英语Starter Unit 2第一课时课时特训答案
人教版六年级上册英语第五单元综合评价课时特训答案
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |