Irradiating Food
Irradiating fruits, vegetables, pork and chicken to kill insects and bacteria has been approved by the Food and Drug Administration over the past decade or so. Irradiation of other meats, such as beef and lamb, is being reviewed. Federal approval does not require that industry adopt the process, and few food processors presently offer irradiated products.
Market studies have shown that many consumers are afraid that eating irradiated foods may cause cancer, despite scientific studies that prove the safety of treated foods. Some people argue that more severe government inspection, higher food-safety standard and more careful-preparation practices by consumers are all that is needed to ensure that food is safe. Consequently, companies currently see no need to spend millions of dollars outfitting processing plants with the equipment necessary for a process that very few shoppers are in favor of.
All supermarkets that sell irradiated food must label the food either directly on the packaging, or, in the case of bulk items like fruits and vegetables, by placing a sign nearby. There is no requirement for the labeling of irradiated food served by chain restaurants or hospitals that buy directly from distributors, nor any regulations for products that contain irradiated ingredients.
Presently, the FDA allows food to be treated with three types of radiation -- gamma rays (伽马射线), high-energy electrons, and X rays -- and sets limits on doses, depending on the type of food. The principle is that the dose to be used for a certain type of food should not exceed the amount that is sufficient to kill most harmful insects and bacteria present in it. Different types of food, because of their molecular compositions, may require different doses of radiation.
Killing insects and bacteria present in foods by irradiating is completely approved by the US government.
A.Right
B.Wrong
C.Not mentioned
第1题
下面关于B-ISDN的叙述中,错误的是()
A.B-ISDN的中文名是宽带综合业务数字网
B.B-ISDN的核心技术是采用准同步传输模式(PDH)
C.B-ISDN的带宽可以在155Mbit/s以上
D.B-ISDN的协议分为三面和三层
第2题
下面关于B-ISDN的叙述中错误的是
A.B-ISDN的中文名称是宽带综合业务数字网
B.B-ISDN的核心技术是采用异步传辅模式(ATM)
C.B-ISDN的带宽可以在155Mb/s以上
D.宽带综合业务数字网的协议分为3面和6层
第3题
下面关于B-ISDN的叙述中正确的是()。
A.B-ISDN的核心技术是采用异步传输模式(ATM)
B.B-ISDN的中文名称是窄带综合业务数字网
C.B-ISDN的带宽可以在1Gb/s以上
D.B-ISDN网的协议分为2面和2层
第4题
A.B-ISDN的中文名是宽带综合业务数字网
B.B-ISDN的核心技术是采用异步传输模式(ATM)
C.B-ISDN的带宽可以在155Mb/s以上
D.B-ISDN的协议分为3面和6层
第5题
下列B-ISDN途述正确的是().
A.B-ISDN要求频带宽,速率范围极宽
B.B-ISDN提供的业务具有相同的实时性
C.分组交换广泛应用于B-ISDN中
第7题
宽带综合业务数字网B-ISDN是以()为核心技术网络。
A.ATM
B.SDH
C.DDN
D.帧中继
第8题
宽带综合业务数字网B-ISDN的数据通信服务主要将采用的技术是()。
A.帧中继
B.ATM
C.电话交换网
D.X.25
第10题
宽带综合业务数字网(B-ISDN) 采用的数据传输技术是 ______。
A.电路交换技术
B.报文交换技术
C.分组交换技术
D.异步传输模式(ATM)
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