Look at the center circles of Diagram（图）A and Diagram B. Which of the centre circles looks larger?

Take a first look and you probably think that the centre circle in Diagram A is smaller than that in Diagram B, But in fact, they are exactly the same size.

Then look at the picture on the right. What do you see? A vase? Or two faces? Does the picture change quickly from one to the other again and again? Maybe or maybe not, but you can never see them at the same time.

“What's happening? Is something wrong with my eyes?” You may wonder at what you see. Don't worry. Here is how it goes:

When we look at things, our eyes send messages to our brains and then our brains interpret（解读）the information. However, sometimes our brains interpret the received information in a wrong way. It seems that our eyes are playing a joke on us. This often happens and we call it “visual illusion”（视觉错误）.

Movie makers often make use of illusions. They make the objects around actors much smaller or bigger than usual. This makes us believe that the actors are much larger or smaller than they usually are. The movies Jurassic Park and Honey I Shrunk The Kids just make use of illusions.

There are certain foods which should never be stored(储存) in the fridge. Some of them may surprise you.

【小题1】 The cold temperature will make it hard. If you have made sandwiches with the bread, then you can store them in it.

We all love to have tomatoes. 【小题2】 The cold air in the fridge stops the ripening(成熟) process. And as we all know, ripening is what gives every tomato more taste. For best results, keep them out.

【小题3】 It needs no help from us. Putting it in your fridge will in fact increase the speed of the crystallization(结晶). This will make honey harder or nearly impossible to use.

If you haven’t opened your watermelons, then there’s no need to put them in your fridge. Research has shown that watermelons can be stored in room temperature. 【小题4】 Watermelons that have been cut open should be put in the fridge. What’s more, they should be covered.

Cucumber(黄瓜) enjoys room temperature. 【小题5】 Cool temperature can make cucumber’s skin(表皮) go bad faster, so find a dry and cool place at room temperature for your cucumber.

Do animals communicate with each other?

This question came to my mind one day when I was sitting outside. 【小题1】 I looked around and saw a cat sitting low on the grass, ready to jump onto the birds. But the cat was too late. The birds suddenly flew to safety. The loud calls had warned them about the danger.

【小题4】 Some animals, like skunks （臭鼬）, send out a strong smell to warn other animals to stay away from them. There are many examples of animals that use body language to communicate.Chimpanzees （黑猩猩）touch hands when they meet. Think of a happy dog moving its tail. Even humans understand this form of dog body language.

【小题5】 But if you watch other animals for a while, you’ll quickly come to know that they also have ways of getting their messages across.