题干

为了探究声音产生的原因,小明和小华一起做了几个实验:小明把手放在喉咙处,大声讲话,感觉喉头振动了;小华把发声的音叉放入水中,可以激起水花.

(1)通过对上面的种种实验现象的分析,你能得出的结论是 ____

(2)小华同学用手使劲敲桌子,发出很大的响声,但是他看到桌子几乎没有振动,为了使看到的实验现象更明显,你的改进方法是: ____

(3)小明、小华等同学在探究出上述问题之后,又提出这样一个问题:声音是怎样从发声物体传播到远处的?针对这一问题,他们经过认真地思考,提出了两种猜想:①声音要传播出去,需要物质作媒介; ②声音要传播出去,不需要物质作媒介;究竟哪一种猜想是正确的呢?小明他们进行了如下的实验:如图所示,随着向外不断抽气,结果发现手机铃声越来越 ____(选填“大”或“小”).由此现象可以推理:猜想  ____ 是正确的。

(4)探究问题的过程通常有下列步骤:

A.提出猜想并作出假设;B.分析归纳;C.得出结论;D.实验研究;E.发现并提出问题。

你认为小明他们的第二个探究活动依次采取的步骤是  ____ (填字母序号)。

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答案(点此获取答案解析)

声音是由于振动产生的,在桌子上放一些小纸屑,小,①,EADBC

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    In 1943, when I was 4, my parents moved from Coeur d'Alene, Idaho, to Fairbanks, Alaska, where adventure was never very far away.

    We arrived in the summer, just in time to enjoy the midnight sun. All that sunlight was fantastic for Mum's vegetable garden. Working in the garden at midnight tended to throw her timing off, so she didn't care much about my bedtime.

    Dad was a Railway Express agent and Mum was his clerk. That left me in a mess. I usually managed to find some trouble to get into. Once I had a little fire going in the dirt basement of a hotel. I had tried to light a barrel(桶) of paint but couldn't really get a good fire going. The smoke got pretty bad, though, and when I made my exit, a crowd and the police were there to greet me. The policemen took my matches and drove me home.

    Mum and Dad were occupied in the garden and Dad told the police to keep me, and they did! I had a tour of the prison before Mum rescued me. I hadn't turned 5 yet.

    As I entered kindergarten, the serious cold began to set in. Would it surprise you to know that I soon left part of my tongue on a metal handrail at school?

    As for Leonhard Seppala, famous as a dog sledder(驾雪橇者), I think I knew him well because I was taken for a ride with his white dog team one Sunday. At the time I didn't realize what a superstar he was, but I do remember the ride well. I was wrapped(包裹) heavily and well sheltered from the freezing and blowing weather.

    In 1950, we moved back to Coeur d'Alene, but we got one more Alaskan adventure when Leonhard invited us eight years later by paying a visit to Idaho to attend a gathering of former neighbors of Alaska.