问题 选择题

学习化学能让我们更好的认世界和了解生活。下列有关化学与生活的说法中正确的是[ ]

A.掏空沼气池前进行灯火试验

B.推广使用聚乙烯塑料包装食品

C.利用洗洁精的乳化功能清除油污

D.绿色食品不含任何化学物质

答案

答案:C

阅读理解

阅读理解

       Take any long piece of paper. Now glue the ends of the paper together. You have made a ring.

       Take a second long piece of paper. Twist the paper once and glue the ends together. Now you

have made a Mobius band. For people studying maths, this band is uncommon.

       This strange band was first made in the 1800s by a German man named August Mobius. Mr. Mobius studied maths. He wanted to find a way to show how this band works with maths. Understand it or not,

this band has only one surface. You can find this out for yourself.

       If you draw a line on the surface of the paper before you twist and glue it, the line is only on one side

of the paper. The paper has two surfaces. However, if you draw a line after you make the Mobius band,

you can follow the line around all sides of the paper. In other words, the Mobius band must have only

one surface.

       It is also very interesting to see what happens when you cut the band. If you cut the Mobius band in

half once down the line you drew, you do not get two Mobius bands. Instead, after you cut the band, it

turns into one large twisted ring. Then, if you cut this ring in half along the middle of the band again, you

get two connected  Mobius bands.

       Try it!

1. What is a Mobius band?

A. A ling piece of paper.

B. A paper ring for people to wear.

C. A metal ring for music.

D. An interesting twisted ring.

2. How can you change the two surfaces of a long piece of paper into one surface?

A. Glue the ends of the long piece of paper.

B. Cut the two surfaces of the paper into one.

C. Draw a line in the middle of the paper.

D. Twist the paper once and glue the two ends.

3. What do you get if you cut the Mobius band along the middle?

A. A long piece of paper.

B. Two long pieces of paper.

C. Two Mobius Bands.

D. One large twisted ring.

问答题 简答题