问题 填空题
定义符合条件
x≤y≤2x
0≤y≤a
x,y∈N
的有序数对(x,y)为“和谐格点”,则当a=4时,“和谐格点”的个数为 ______.
答案

当a=4时,

∵0≤y≤4,x,y∈N,x≤y≤2x

当y=0时x=0;

当y=1时,满足x≤1≤2x的x有1;

当y=2时,满足x≤2≤2x的x有1,2;

当y=3时,满足x≤3≤2x的x有2,3;

当y=4时,满足x≤4≤2x的x有2,3,4

故当a=4时,“和谐格点”的个数为1+1+2+2+3=9

故答案为9

阅读理解

阅读理解。

     London is one of the oldest cities in the world. It is also one of the biggest. But New York is big, too. It

is as big as London if it isn't bigger. There are many streets in New York, beautiful shops and big factories in

it. The streets in New York are just as crowded as in London. And the New York buses carry more people

each day than the London buses.

     There are a lot of places in London. New York isn't as old as London, and it hasn't many old buildings.

The buildings in London are as high as in New York.

     London has more parks than New York. But some parks are much smaller than the ones in New York.

     Now there is a school in New York. It has no lessons every day. It has no class teachers and no school

buildings. The students themselves learn and renew their lessons. They are 15 to 18.They live near the city.

And the students study very hard. They know a lot about different kinds of work in the city. The work of

the school is the best work in the world. The people like it very much and want to do it better.

1. The streets in London are ______ those in New York.[ ]

A. as big as

B. newer than

C. just as crowded as

D. better than

2. In the passage the writer ______. [ ]

A. says New York is larger than London

B. compares (比较) New York with London

C. says he likes New York as much as London.

D. tells us a story about New York

3. In New York, ______. [ ]

A. buses carry more people to the parks

B. more people go out by bus than in London

C. there are more parks

D. there are more schools

4. Which is right? [ ]

A. All the parks in London are smaller than the ones in New York.

B. There is a school without class teachers or school buildings in New York.

C. People don't know the other kinds of work besides the work of school.

D. New York has many old buildings.

5. The students of the school in New York ______. [ ]

A. have their lessons in factories

B. are 15 to 18 years old

C. are all going to be teachers

D. don't study at all

问答题 简答题