问题
多项选择题
NK细胞杀伤病毒感染细胞的特征是()
A．无需抗体的协助
B．直接杀伤
C．干扰素促进杀伤
D．需补体的协助
E．有特异性
答案
参考答案：A, B
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NK细胞杀伤病毒感染细胞的特征是()
A．无需抗体的协助
B．直接杀伤
C．干扰素促进杀伤
D．需补体的协助
E．有特异性
参考答案：A, B
Directions: For each blank in the following passage there are four words or phrases marked A, B, C and D. Fill in each blank with the word or phrase that best fits the context. For several years, Americans have enjoyed teleshopping---watching TV and buying things by phone. Now teleshopping is starting in Europe. In some __46__ countries, people can turn on their __47__ and shop for clothes, jewelry, food, toys and __48__ things. Teleshopping is becoming popular in Sweden. __49__, the biggest Swedish company sells different kinds of things on TV in fifteen European countries, and in one year, it makes $10 million. In France, there are two teleshopping channels, and the French __50__ about $ 20 million a year in buying things through those channels. In Germany, __51__ last year teleshopping was only possible on one channel for one hour every day. Then the government allowed more teleshopping. Other channels can __52__ for telebusiness, including the largest American teleshopping company and a 24-hour teleshopping company. German __53__ are hoping these will help them sell more things. Some people like teleshopping because it allows them to do their shopping without __54__. With all the traffic problems in cities, going shopping is not an easy thing. But at the same time, other Europeans __55__ like this new way of buying things. They call __56__ “junk on the air.” Many Europeans usually worry about the quality of the things __57__ on TV. They think high quality is the most important thing, and they don’t believe they can be sure about the quality of the things __58__. The need of high quality means that European teleshopping companies will have to be __59__ the American companies. They will have to be more careful about __60__ of the things they sell. They will also have to work harder to sell things that the buyers cannot touch or see by themselves.
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