问题 选择题

下列图形中,只用一种作平面镶嵌,这种图形不可能是(  )

A.三角形

B.凸四边形

C.正六边形

D.正八边形

答案

A、任意三角形的内角和是180°,放在同一顶点处6个即能密铺,不符合题意;

B、任意四边形的内角和是360°,放在同一顶点处4个即能密铺,不符合题意;

C、正六边形每个内角是120°,能整除360°,故能密铺,不符合题意;

D、正八边形每个内角是180°-360°÷8=135°,不能整除360°,不能密铺,符合题意.

故选D.

单项选择题
阅读理解

阅读理解。

     A primary school teacher who left a class of 25 pupils in tears after she told them Santa Claus did

not exist has been fired. When excited youngsters became rowdy as they talked about Santa, the supply

teacher said out suddenly, "It's your parents who leave out presents on Christmas Day."

     The class of sevenyearolds at Blackshaw Lane Primary School, Royton,Greater Manchester burst

into tears and told their parents when they arrived home. Mothers and fathers then complained about the

incident and were sent a letter by the school saying the teacher, who only worked at the school for one

day last week, has been disciplined.

     The school has now said it will not hire her again.

     One father said, "My son came home and said that his teacher had told the class that Santa doesn't

exist and it's their mum and dad that put out presents for them. Obviously, they were all talking about

Christmas and being a bit rowdy. She just came straight out with it."

     "My son was in tears and so was everyone else in the class-especially as it was so close to

Christmas. I thought it was wrong. He was crazy about it. He's only seven years old and it's part of the

magic of  Christmas to him."

     "We told him that she did not believe in Father Christmas because of  her religion and he's fine now."

     "The father described the incident as 'shocking' and believed it was done with malicious

intent(恶意地). A lot of parents were angry and complained to the school.The teacher,who was

supplied by Rochdale and Oldham Supply Agency,is still listed and will work with other schools,"the

agency said.

     However,t he head teacher in Angela McCormick refused to comment on the incident.

1. Who felt the angriest about the incident?

A. The teacher who was fired.

B. The pupils who were in tears.

C. The parents whose children cried.

D. Santa Claus the teacher talked about.

2. The sevenyearold children cried because of ________.

A. their teacher's leaving      

B. the letters by the school

C. something about Santa Claus  

D. the presents left out by the parents

3. We can infer from the passage that ________.

A. the teacher was fired and couldn't continue her career in teaching

B. the parents complained about the discipline of the school

C. the little pupils felt disappointed after hearing the news told by the teacher

D. in reality,Santa Claus exists and gives out presents once a year.

4. What's the meaning of the underlined word"rowdy"?

A.Surprised.      

B.Noisy.

C.Discouraged.  

D.Annoyed.