问题 填空题

若干个1与2排成一行:1,2,1,2,2,l,2,2,2,1,2,…,规则是:第1个数是l,第2个数是2,第3个数是1.一般地,先写一行1,再在第k个1与第k+1个1之间插入k个2 (k=1,2,3,…).那么前2005个数的和是______.

答案

观察分析得:值为1的数的序号是:

1,3,6,10,…即 1,1+2,1+2+3,1+2+3+4,…

其中1+…+62=1953,1+…+63=2016

所以:

 第1953个数是1,第2016个数是1,第2005个数必然是2,

则:前2005个数的和是62×1+×2=3948.

故答案为:3948.

阅读理解

阅读理解。

     Penguins lie together, but each pair has a little piece of ground of their own. When a penguin wants to walk

through its neighbour's ground, it must ask for permission. If it does not, it will have to fight. Penguins come

and go all day. They catch fish and look after their children.

      All penguins are good parents- the male penguins are perhaps the best parents in the world. They walk in

the middle of the dark Antarctic water. They choose their wives in the dark. They can only hear them-not see

them. Then the female penguins lay their eggs and go away for about two months. The males look after the

eggs. If the eggs get cold, there will be no chicks. There is no food. The snow falls and the wind

blows-sometimes at 150 kilometres an hour. The penguins do not move. When females return from the sea,

they will not remember their husbands. It does not matter. Only one thing matters - the eggs. Male penguins

never fight unless a penguin leaves a chick for a minute. Then they fight because they all want it. They are

strange and wonderful birds.

1. It seems interesting and unusual that the male penguins choose their wives ______.

A. when the female penguins return from the sea

B. just by hearing in the darkness

C. each time they see the lovely females

D. after they have had their own grounds

2. It is ______ that take care of the eggs.

A. the male penguins

B. the female penguins

C. both the husbands and the wives

D. the penguins that lost in the fight

3. Only when ______ can a penguin walk through its neighbour's ground.

A. it gets wet

B. it has become a father

C. it gets married

D. it gets permission

4. When the females return from the sea, they will ______.

A. live with their husbands

B. look after the eggs

C. get food for their husbands and children

D. not remember their husbands

5. Which of the following statements is NOT true?

A. Female penguins often have their new husbands.

B. Male penguins fight when choosing their wives.

C. Female penguins take care of the eggs.

D. Male penguins use their ears to choose wives.

单项选择题 A2型题