题干

2016年里约奥运会正在如火如荼的进行着,里约市交警部门为了保障奥运期间交通安全畅通,为了能够准确检测车辆行驶情况,在公路上安装了超声波测速仪,图甲是超声波测速仪测量车速的示意图,测速仪发出并接收超声波脉冲信号,根据发出和接收到的信号间的时间差,测出被测物体的速度。图乙中P1、P2是测速仪发出的超声波信号,n1、n2分别是P1、P2由汽车反射回来的信号。设测速仪匀速扫描,P1、P2之间的时间间隔t=1.0 s,超声波在空气中的传播速度是v=340 m/s,若汽车是匀速行驶的,则根据图乙可知,汽车在接收到P1、P2两个信号之间的时间内,前进的距离是多少?汽车的速度是多大(保留三位有效数字)?

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答案(点此获取答案解析)

解:由题图乙知,超声波信号P1、P2间隔30格,因时间t=1.0 s,故1格时间为 30
1
s,发出超声波信号P1到接收到反射信号n1之间的时间间隔t1=10×

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阅读理解

    Why read, and sometimes even write poetry? That question is not difficult to answer if we change the word poetry to songs.

    I sing when I feel good. When I sing my favorite songs, I feel even better. Sometimes when I am listening to music and to the song words, I feel that it was written for me. A good song always makes me feel something. There are songs that I sing in my head between classes and songs that I want to sing when the school bell rings by the end of the day. They help me get through the day.

    They are like bright and warm colors in the middle of grays and shades. I like songs about love and friendship. The extraordinary thing is that my feelings are more special when I sing my favorite songs in English.

    I also like reading. I used to avoid poetry until an e-friend told me I should recite poems and not look up the meaning of the words. Poetry uses many difficult words and idioms, but the best thing is to just forget about them. In the beginning I felt quite strange. Now I always lock the door. Reading aloud gives you a strange feeling, but when you have some practice and fall into the rhythm, and the sounds of the words, it is really a special experience.

    I started with small poems, but now I think I most like long poems. I have different feelings with different poems. When I have had a bad day at school, I read Keats and forget everything. When I am sad I read Wordsworth by the light of a candle. When the poem is finished, I close the book and my sadness is gone.