问题 填空题

科学考察工作者为了测海底某处的深度,向海底垂直发射超声波,经过1.4s收到回波信号。该处海水深_________m(声音在海水中的传播速度约1500m/s)。这种方法________(填“能”或“不能”)用来测量地球和月球之间的距离。因为_____________________。

答案

1050 ,不能,真空不能传声

(1)声音从海面传到海底的时间为t="1" /2 ×1.4s=0.7s,

那么海水的深度为s=vt=1500m/s×0.7s=1050m,

(2)由于地球与月球之间是真空,而声音不能在真空中传播,所以不能用这种方法测量地球和月球之间的距离.

阅读理解

阅读理解。

     Climbing a mountain is hard work. But one step (脚步) after another finally brings a person to the

top. Along the way, he can stop and look around. And the higher he climbs, the more wonderful his view

is. If he keeps climbing, he will have a new world before him. He will have a new way to see everything.

     Now learning a foreign language is something like climbing a mountain. This new language can give

you a new view of life. And it is more than a look at the surface of things. It can open the way into

people's minds and hearts and into a culture that is very different from your own culture. This will make

you richer, richer in things that money can't buy. Even though you never set foot (踏上) on a ship or a

plane, you can be an armchair traveler through books.

     The mountain climber stops now and then to enjoy the scenery around him. Reading is just like this.

If you are interested in it, you will find fun in books.

1. Is climbing a mountain easy?

    ____________________________________________________________

2. What will he have if he keeps climbing?

    ____________________________________________________________

3. Can learning language open the way into people's minds and hearts?

   ____________________________________________________________

4. How will learning language make you?

    ____________________________________________________________

5. Where will you find fun if you are interested in reading?

    ____________________________________________________________

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