问题 填空题

声音是由物体______产生的,在15℃时,声音在空气中的传播速度是______m/s.

答案

声音是由发声体的振动产生的,声音的传播需要靠介质,声音在不同介质传播的速度不同,声音在15℃的空气中的传播速度是340m/s.

故答案为:振动;340.

阅读理解

阅读下面短文,简要回答所给问题。

     The first Earth Day was in 1970. People were beginning to worry about what we were doing to our

environment. So they set up Earth Day to tell everyone about their worries.

     In 2007 organizers m over 150 countries planned over 4,000 big events. But Earth Day is not just about

marches (游行) and big events. In the week around Earth Day (22 April) there were many thousands of

smaller, local events. These events dealt with environmental problems in the neighborhood.

     The World Wide Fund for Nature made a list of 5 things that each person could do to save the environment. 

     * Don't leave the tap running.

     * Turn off lights when you leave a room.

     * Turn off your computer every night.

     * Wash your clothes, and yourself, in warm or cold water, not hot water.

     * Dishwashers use as little water as possible. If we all do at least 2 0f these all the time, we can make a big

difference.

1. What is the purpose for people to set up Earth Day?

    ________________________________________________________________________________

2. When is Earth Day? 

    ________________________________________________________________________________

3. What should people do when the water keeps running from a tap? 

    ________________________________________________________________________________

4. Does the word "dishwashers" mean "machines for washing dishes"?

    ________________________________________________________________________________

5. Besides the five, what else can you do to save our environment? (One example is OK.) 

    ________________________________________________________________________________

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