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问题 填空题

将参加夏令营的600名学生编号为：001，002，…600，采用系统抽样方法抽取一个容量为50的样本，且随机首次抽得的号码为003．这600名学生分住在三个营区，从001到300在第Ⅰ营区，从301到495住在第Ⅱ营区，从496到600在第Ⅲ营区，三个营区被抽中的人数依次次为______．

答案

依题意可知，在随机抽样中，首次抽到003号，以后每隔12个号抽到一个人，

则分别是003、015、027、039构成以3为首项，12为公差的等差数列，

故可分别求出在001到300中有25人，在301至495号中共有17人，则496到600中有8人．

故答案为：25，17，8．

单项选择题

The fridge is considered a necessity. It has been so since the 1960s when packaged food first appeared with the label: "store in the refrigerator. "
In my fridgeless fifties childhood, I was fed well and healthy. The milkman came daily, the grocer, the butcher, the baker, and the ice cream man delivered two or three times a week. The Sunday meat would last until Wednesday and surplus bread and milk became all kinds of cakes. Nothing was wasted, and we were never troubled by rotten food. Thirty years on, food deliveries have ceased, fresh vegetables are almost unobtainable in the country.
The invention of the fridge contributed comparatively little to the art of food preservation. A vast way of well tried techniques already existed—natural cooling, drying, smoking, salting, sugaring, bottling…
What refrigeration did promote was marketing—marketing hardware and electricity, marketing soft drinks, marketing dead bodies of animals around the globe in search of a good price.
Consequently, most of the world’s fridges are to be found, not in the tropics where they might prove useful, but in the wealthy countries with mild temperatures where they are climatically almost unnecessary. Every winter, millions of fridges hum away continuously, and at vast expense, busily maintaining an artificially cooled space inside an artificially heated house—while outside, nature provides the desired temperature free of charge.
The fridge’s effect upon the environment has been evident, while its contribution to human happiness has been insignificant. If you don’t believe me, try it yourself, invest in a food cabinet and turn off your fridge next winter. You may miss the hamburgers, but at least you’ll get rid of that terrible hum.

Who benefited the least from fridges according to the author

A．Inventors
B．Consumers
C．Manufacturers
D．Traveling salesmen
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填空题

社会主义改造基本完成后，党和全国人民的主要任务是（）
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