题干

将正整数1,2,3,4,…,n2(n≥2)任意排成n行n列的数表.对于某一个数表,计算各行和各列中的任意两个数a,b(a>b)的比值
a
b
,称这些比值中的最小值为这个数表的“特征值”.若aij表示某个n行n列数表中第i行第j列的数(1≤i≤n,1≤j≤n),且满足aij=i+j-i-1ni+n-1+j-1n,当n=4时数表的“特征值”为____ .
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5
4

同类题2

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    A 15-year-old student who invented a flashlight(手电筒) getting power from the holder's body heat is going home today from California with a big prize and a chance to do further research.

    Ann Makosinski was the only Canadian among the four winners at Google's international science competition. Thousands of young scientists from around the world took part in the competition.

    Winning the science and technology competition was "a surprise". Ann said, "I think it will have a great influence on my future."

    Ann thanked her family for encouraging her interest in science and said that her first toy was a box of transistors(晶体管).

    Ann's prize includes $ 25,000 and a "once in a-lifetime expericnce" from Google for her Hollow Flashlight, which has no moving parts or batteries.

    The idea for the invention came from seeing unwanted batteries and her friend's experience. When Ann visited a friend in the Philippines, she saw the friend couldn't study when it became dark because there was no electricity or light. She saw the need for a flashlight that has no batteries - Hollow Flashlight.

    In her project, Ann wrote "I made two flashlights that do not use any batteries or harmful materials. They do not create any noise and will always work. The flashlight needs at least a 5℃ temperature difference between the holder's body and the environment around to produce light."

    A video of Ann explaining how she creatcd the flashlight has been watched more than 1.4 million times on the Internet.

    Though Ann was successful, she has not made a decision about her career path. Ann hopes that she can find a way to join her love of film and science together.

    The four winners were chosen from 15 final competitors from eight countries. The competition attracted thousands of students in 120 countries.


同类题3

   A 10-year-old boy decided to learn judo though he had lost his left arm in a car accident. The boy was doing well, so he couldn't understand why, after three months of training, the master had taught him only one move.
   “ Master,” the boy finally asked, “shouldn't I be learning more moves?"“ This is the only move you know, but this is the only move you'll ever need to know,” the teacher answered.
   Several months later, the teacher took the boy to his first competition. Surprising himself, the boy easily won his first two matches. The third match proved to be more difficult, but after some time, his opponent (对手) became impatient and charged; the boy skillfully used his one move to win the match. Still amazed by his success, the boy was now in the final.
  This time, his opponent was bigger, stronger, and more experienced. Soon after the match started, the boy seemed to lose. Thinking that the boy might get hurt, the judge called a time-out. He was going to stop the match when the teacher appeared. “ No,” the teacher said, “Let him continue.” A short time after the match carried on, his opponent made a careless mistake. At once, the boy used his move to pin (压住) him. The boy won the match and the competition.
  On the way home, the boy asked the teacher what was really in his mind. " Why could I win the competition with only one move?" The teacher answered. "First, you've mastered one of the most difficult throws in judo. Second, your opponent can only attack your left arm to win you.”
根据短文内容完成下面的表格,每空一词。

Title: One’s weakness can become his____ 
A boy had lost left arm, ____  he decided to learn judo
After three months of training, the master taught him only one move.
His first____ First three matchesHe won.
FinalHis opponent was bigger, ____  and more ____ .
At the ____ , the boy seemed to lose the match.
The judge was____  that the boy might get hurt and called a time-out.
His opponent made a mistake. The boy used his move and pinned him.
He became the ____  of the match.
____ 1. He had almost mastered one of the most difficult throws in all of judo.
 The opponent can win the match by ____  your left arm.