单项选择题：进程调度的关键问题是选择合理的( )和进行恰当的代码转换。A．时间片间隔 B．调度

题型：单项选择题

Did you ever wonder how some of your favorite foods, products or toys came about? Believe it or not, they may have been an accident, or a failure of some other intention. Below, we found three mistakes we’re thankful for turned out to be what they are.

1. Most historians hold that the Chinese invented fireworks in the 9^th century when they discovered how to make gunpowder. Story has it that a Chinese cook accidentally mixed together what were then considered common kitchen items and noticed they burnt. When put tightly in a bamboo tube and lit, it blew up.

2. In May of 1886, a law led John Pemberton, a pharmacist(药剂师), to rewrite the formula(配方) for “Pemberton’s French Wine Coca”, his popular headache treatment. Containing sugar instead of wine as a sweetener, the outcome became something for Coke, which was later mixed with carbonated(碳酸) water. His bookkeeper suggested the name Coca-Cola because he thought the two C’s would look good together, which is how what we call Coca-Cola, a world-wide drink came into being.

3. During World WarⅡ, scientists at the University of Birmingham invented the magnetron(磁控管)—an important heat-producing part of the microwave oven. While working for Raytheon Corporation after the war, the American engineer Percy Spencer was testing the magnetron when a chocolate bar in his pocket melted. He went on to test other foods including popcorn kernels(仁), and found it to be a much more efficient way to cook. In 1947 Raytheon came out with the first restaurant microwave oven, which was six feet tall and weighed 750 lbs.

小题1:The right time order of the three inventions should be ________.

A．fireworks, the microwave and Coca-Cola

B．fireworks, Coca-Cola and the microwave

C．Coca-Cola, fireworks and the microwave

D．the microwave, Coca-Cola and fireworks小题2:Percy Spencer found the microwave efficient in cooking when he was ________.

A．looking for a way to melt his chocolate

B．trying to know how a magnetron could cook

C．working to know how the magnetron works

D．asked to invent a restaurant microwave oven小题3:The underlined phrase “ blew up” might mean _______ in Chinese.

A．爆炸

B．膨胀

C．升华

D．蒸发小题4:What can we learn from the above invention stories?

A．Experiments make great inventors of our time.

B．Nothing is impossible if one tries each day.

C．Inventors come out of hard work at any time.

D．A small incident may lead to a great invention.

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进程调度的关键问题是选择合理的( )和进行恰当的代码转换。A．时间片间隔 B．调度

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