题目内容
To his cosmopolitan mind such deviations from the social ______ were no more than are the
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A Canadian researcher has discovered that sound travels 【21】______ air more than one-half kilometer an hour slower than had been believed. The discovery has surprised many engineers and scientists who learned they had been 【22】______ the wrong speed of sound for many years.
The speed of sound in air had been【23】______ to be three-hundred-thirty-one-point-two-nine meters a second. But Doctor George Wong found, 【24】______ accident, that the speed of sound is only three-hundred-thirty-one-point-one-three meters a second. That is a difference of about sixteen centimeters a second.
Doctor Wong is a member of the National Research Council of Canada. He was studying ways to 【25】______ exactly the sound created by microph ones. One of his experiments 【26】______ a number he could use to find the speed of sound. He was 【27】______ to learn that the speed of sound was slower than scientists had thought.
To explain the difference, Doctor Wong spent eighteen months 【28】______ past test research on the speed of sound. He finally found the 【29】______ of the difference. It was a mathematics mistake 【30】______ in Nineteen-Forty-Two by physicist H-C Hardy.
Doctor Wong's 【31】______ does not mean a big change for the science of sound. This is 【32】______ Doctor Hardy and Doctor Wong measured the speed of sound for what is called" standard air".
Standard air exists only 【33】______ thought. It is a way for scientists to agree 【34】______ the same speed of sound. 【35】______ the air around us, standard air always has a temperature of zero degrees Celsius and the same atmospheric pressure 【36】______ the air at sea level. Standard air always has same amounts of nitrogen, oxygen, carbon dioxide and 【37】______ gases. And in standard air, the speed of sound does not change.
The change in the new speed of sound is 【38】______ small to affect the work of most sound scientists and engineers. But scientists say Doctor Wong's discovery may 【39】______ improve instruments 【40】______ use the speed of sound to measure very short distances.
【21】
Under the rules laid down by the bank there is a ______ on the amount of money you can get
For many centuries and in all countries people have studied the weather and tried to make weather forecasting. Sometimes distant objects such as hills and tall trees seem to be very clear and near. This is a sign of much water vapor in the air ,and therefore rain will probably come. Rings round the sun are a sign of coming rain. Many people feel pain in their bones. This is a sign of the coming of wet weather. Some birds fly high if fine weather is coming. They fly near the ground if rain or stormy weather is on the way. It is probably because of the insects which they are hunting that they fly low. If you see a rainbow during rainy weather, this is a sign that the weather will become clear and fine. Such rainbows always come in the evening. If a fog appears in the morning just about sunrise then the day will be warm. If the stars twinkle clearly at night, then fine weather will continue. If the sunset is mostly red in color, then the following day will be fine. If the rainbow appears in the morning, rainy weather will probably come. Most of the above sayings have been made by people who have used their eyes and brains to make weather forecasting.
What kind of weather will it be When distant objects such as hills and tall trees seem to be very clear and near？
邓小平理论形成的时代背景是（）
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