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【单选题】
请判断下列叙述中哪一个是正确的( )A.
时分多路复用是将物理信道的总带宽分割成若干个子信道，该物理信道同时传输各子信道的信号
B.
虚电路传输方式类似于邮政信箱服务，数据报服务类似于长途电话服务
C.
多路复用的方法中，从性质上来说，频分多路复用较适用于模拟信号传输，而时分多路复用较适用于数字信号传输
D.
即使采用数字通信方式，也还需要同模拟通信方式一样，必须使用调制解调器
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【简答题】Faced with various natural d_______, we Chinese people should never be frightened and give up
【单选题】Business letters must always be _____, but we should write in a natural way to friends.
A.
official
B.
full-dress
C.
formal
D.
ceremonial
【简答题】We should not require native-like pronunciation from every one. What should be our realistic goal? : the pronunciation should be smooth and natural : the pronunciation should be understandable to the ...
【多选题】Some people strongly agree that we should return to more natural methods of food production, such as organic farming, even if this means that we produce food less efficiently.They believe this because...
A.
More people will need to be employed, and fewer people will be available to do work that will help the country develop economically.
B.
Producing food less efficiently could lead to food shortages.
C.
It is better for teh enviroment to produce food using fewer chemicals such as pesticides and herbicides.
D.
Organically produced food is no more nutritious than food produced using pesticiedes and artificial fertilisers.
E.
Naturally produced food tastes better than food produced using more artifical methods.
F.
food that has been produced without preservatives is less likely to stay fresh, so more food may be wasted.
G.
Man-made chemicals used in modern methods of food production could be harmful to human health.
【简答题】If we want to deal with the association(交往) between boys and girls properly, here are some “dos and don’ts” for you to follow: Keep a normal and healthy state of mind. Our schools and classes are made...
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