How to make a geometry puzzle(几何谜题) that most people can’t figure out?

You’ll need:

＊ Square piece of light cardboard or heavy paper

＊ Scissors

＊ Four brass paper fasteners

＊ Hole puncher

1 Cut the paper into four equal strips.（相同大小的）

Punch holes near the ends of each strip.

2 Make a square with fasteners.

3 Hold two opposite sides, gently pull them outward, and twist（扭转） your hands inward at the same time.

What happened?

You can reshape the square into a ring, and flip（翻转） that ring back into a square.

Give the square to 10 people and ask them,“can you make this into a ring?”   and see how many can.

There’s a mathematical science called topology（拓扑学）.

It studies shapes that can be turned into other shapes like this.

【小题1】How many kinds of tools will you need in this experiment?

A．Three

B．Four

C．Five

D．Six

【小题2】What should you do after cutting the paper into four equal strips?

A．Make holes with puncher in each strip.	B．Make a square with fasteners.
C．Pull the opposite sides inward.	D．Twist your hands outward.

【小题3】Which of the following can probably happen?

A．You can’t turn the square into a ring.

B．You can turn the ring into a square.

C．You can’t turn the square into any other shape.

D．You can turn the ring into any other shape except a square.

【小题4】The passage is from a book about ____________

A．history

B．biology

C．science

D．sports

【小题5】What is the main purpose of the passage?

A．To tell us a funny story.	B．To teach us an important lesson.
C．To explain how to do an interesting game.	D．To show an example of topology.