题干

如图所示,用手拨动塑料尺,发出的声音是由塑料尺____产生的,经____传入人耳;塑料尺振幅越大,声音的____越大;若改变塑料尺伸出桌面的长度,会使声音的____发生改变.

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振动,空气(气体),响度,音调

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    I travel a lot, and I find out different “styles” of directions every time I ask “How can I get to the post office?”

    Foreign tourists are often confused in Japan because most streets there don't have names; in Japan, people use landmarks(地标)in their directions instead of street names. For example, the Japanese will say to travelers, “Go straight down to the corner. Turn left at the big hotel and go past a fruit market. The post office is across from the bus stop.”

    In the countryside of the American Midwest, there are not usually many landmarks. There are no mountains, so the land is very flat; in many places there are no towns or buildings within miles. Instead of landmarks, people will tell you directions and distances. In Kansas or Iowa, for example, people will say, “Go north two miles. Turn east, and then go another mile.”

    People in Los Angeles, California, have no idea of distance on the map; they measure distance in time, not miles. “How far away is the post office?” you ask. “Oh,” they answer, “it's about five minutes from here.” You say, “Yes, but how many miles away is it?” They don't know.

    It's true that a person doesn't know the answer to your question sometimes. What happens in such a situation? A New Yorker might say, “Sorry, I have no idea.” But in Yucatan, Mexico, no one answers “I don't know.” People in Yucatan believe that “I don't know” is impolite. They usually give an answer, often a wrong one. A tourist can get very, very lost in Yucatan!