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问题 选择题

物质的下列性质中，属于化学性质的是 [ ]

A.硬度大             

B.沸点高             

C.能燃烧             

D.密度大

答案

答案：C

问答题

小红是一个爱思考、爱观察的同学，有一次，在她欣赏了一场音乐会后，想到了如下问题，请你帮她回答一下：

（1）琴声、歌声是通过______传播到小红耳朵的，当时的气温为25℃，则其声速为______．

（2）小红能清楚的分辨出哪是提琴声、哪是小号声，原因是______．

（3）女高音歌唱家演唱时声音的______高，男低音歌唱家演唱时声音的______大．（填音调、音色或响度）

（4）小红观察到乐手在演奏提琴、吉它、二胡等弦乐器时，这些乐器的弦在振动．并且，弦张的越紧，振动的越______，发声的音调越______．

（5）小红猜测：在弦张紧程度相同的条件下，发声的音调还可能与弦的粗细、长短、及弦的材料有关．于是，她想通过实验来探究一下自己的猜想是否正确．下表是她在实验时控制的琴弦条件．

琴弦的材料琴弦的长度/cm琴弦的横截面积/mm2
A钢200.3
B钢200.7
C尼龙丝300.5
D铜400.5
E尼龙丝400.5
1．如果小红想探究弦发声的音调与弦的粗细的关系，你认为她应该选用表中编号为______的琴弦．

2．探究过程通常采用下列一些步骤：①实验研究，②分析归纳，③提出问题（或猜想），④得出结论等．你认为小兰要完成本探究的全过程，所采取步骤的合理顺序应该是______．

3．在上述探究过程中，主要用到了______的研究方法．请你再写出一个初中物理中用到的这种方法的实验名称______．

（6）问题探讨：小红想进一步了解有关声音的一些知识，于是她查找了如下资料：

共鸣

两个发声频率相同的物体，如果彼此相隔不远，使其中一个物体发声，另一个也有可能跟着发声，这种现象就叫“共鸣”．

有趣的是：几乎随便什么容器里的空气（叫做空气柱），也会同发声物体共鸣．拿一个发声体靠近容器口，如果频率适当的话，那么，空气柱就会发生共鸣，使声音大大增强．根据声学家的研究，只要波长等于空气柱长度的4倍，或4/3倍、4/5倍…的声音，传入容器后就能引起共鸣．这就是我们把耳朵贴在热水瓶等容器口上能听见嗡嗡声的原因．

1．什么条件下空气柱会发生共鸣？

2．一把普通热水瓶内部高度大约是30厘米，则波长为______厘米的声音传入热水瓶，会引起共鸣．

3．在日常生产和生活中，哪些地方利用了此现象？请举一例．
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阅读理解

阅读理解。

     Readers Digest在网上公布了2008年Hero 的候选人的事迹。

     A. After the September, 11 Event, Rossmiller began to identify would-be terrorists in e-mail exchanges. So far, she has tracked down a few arms dealers. Faced with death threats, the mother of three says,

"With anything important, you have to take risks."

     B. "Stop them!" a passer-by yelled. "They stole a lady's purse!" Kevin Croskey ran after two young

men. One of the teenagers pulled a weapon. He threw himself on the kids and sent them to the police

station.

     C. In 2003, Mark and three other family members started to clean up the worsening bay in California. So far, they've poured $100,000 of their own money into this campaign and enlisted 1,100 others to try to return the bay to a safe, clean environment.

     D. A tornado struck a nursery school in Alabama and trapped teachers and kids in the game area.

Minutes later, Justiss and a line of gathering volunteers rushed into the area and saved 31 kids they knew

nothing about.

     E. Phillips searched for five years before she finally found her missing sister. In the process, she learned more about the missing people and their family members and founded a website to assist people looking

for loved ones.

     F. A man was lying on the sidewalk, wildly kicking at two dogs which were biting him. Griggs stopped his car and grabbed a pipe on the ground. A direct blow made the male dog flee. Then Griggs used the

pipe to strike the female dog until she left. Next he helped to carry the man to the hospital.

请阅读以下人员的信息,与他们所选的Hero 进行匹配：

1. Pearce is a magazine editor, responsible for providing information for those who searched for their relatives and friends. She appreciated the hard work people paid to get the lost one back.

2. Pickering insists all men are becoming colder, minding their own business. He thinks a hero should be the one who helps strangers out of trouble at the cost of his own life.

3. Fiona recently witnessed a theft but was not brave to stop it. She admired those with courage in face of a criminal.

4. Eliza started her own business with little money and suffered several severe failures. But she made herself on the Rich List, insisting that nothing is impossible if we take risks.

5. Higgins works for a hospital. In his spare time, he volunteers to do something to develop the environment-conscious public. He believes it is everyone's duty to treasure our earth.

1. ________   2. ________   3. ________   4. ________   5. ________
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