Throw a stone across the water and see how many times it skips (跳) .Have you played this game before? The more times the stone skips,the more cheers you will get. But do you know the secret behind its success?

   With the help of high-speed cameras,scientists at Brigham Young University in the US have found out the secret skills of stone skipping.

   The first step is to choose the right stone. " Use flat round stones (disc-shaped stones) , and find a weight that allows you to put a lot of spin on them," Tadd Truscott,an assistant professor,told The Huffington Post. Discs are usually easier to skip than rounded stones.

   Then,here comes the key part： find the right angle. According to the Guinness World Records,the world record for stone skipping is 88 skips set in 2013 by an American called Kurt Steiner.

   Professor Truscott said the skill depends on what angle the thrower chooses to throw a stone at. The best angle for discshaped stones is close to 20 degrees (度) . But the heavier the stone is,the flatter this angle should be.

   If you find 20 degrees hard to measure,you can try another way. Give a great deal of backspin (下旋) to a rounded stone,so it will go under the water and then pop up and out of the water.

    "To make it,you need to throw the stone at a much higher angle than for the usual skipping,M Truscott said to The Huffington Post.

71. What is the article mainly about?

It is mainly about.

72. How did scientists find out the secret skills of stone skipping?

They found out them.

73. What are the secret skills?

They are.

74. Who is Kurt Steiner according to the article?

He is an American who set in 2013.

75. What is the best angle for disc-shaped stones?

The best angle is.

  71. the secret skills of stone skipping   72. with the help of high-speed cameras   73. choosing the right stone and finding the right angle   74. the world record for stone skipping   75. close to 20 degrees  

題目來源：2016金考卷特快專遞陜西中考45套匯編英語第六年第五版 > 陜西省中考命題研究專家原創(chuàng)卷（十一）

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