In 2003, we won the battle（战役)against SARS, which killed about 1,000 people around the world. At the moment we are fighting against COVID-19. In human history, there were many fights against epidemic(流行病) and plagues(瘟疫) , which were serious and changed the development of human history. Here are some of them.

Plague of Athens（雅典）

In the second year of the Peloponnesian War (431 BC-404 BC), when a victory(胜利) seemed within reach, a great plague hit Athens. The plague killed about 250,000-300,000 people. That means it caused the death of one in every three people in Athens. People believe that this plague caused the fall of the country.

Black Death

The Black Death first broke out in central Asia and was carried by fleas(跳蚤) on rats. People’s infected skin(感染的皮肤) would turn black in places. It killed about 25-30 million people in the 14th century. Because of the illness, there were not enough farmers in Europe.

The Epidemic of 1918

The epidemic broke out in Spain in late spring of 1918, and in several months, it had killed more people than any other illness in the history. It caused about 50 million deaths in the world, far more than the deaths caused by World War I. The epidemic changed societies around the world.

Courage is often thought to be one of the important spirits everyone needs. Then what is courage? 【小题1】 One isn’t necessarily born with courage, but one is born with potential(潜力). Kids build courage as they are growing up.

Many people talk about connections between courage and fear. 【小题2】 If there is no fear, there is no need for courage. That is to say, courage is the ability to do what makes you feel afraid. Courage doesn’t only mean great actions such as saving one’s life or taking a big risk. 【小题3】 For example, we show courage when we raise our hand to answer a hard question during class or try a new sport.

Courage is in everyday choices we make. Can you be kind to the new kid in class? 【小题4】 Or can you stand up for someone in need? Often, these things don’t come with praise, but they need courage.

【小题5】 When we become brave enough to face failure, we’ll be more willing to try new things and try again after we fail. Courage doesn’t always shout. Sometimes courage is the little voice at the end of the day that says, “I’ll try again tomorrow.”

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. In fact, they are exactly the same size.

Then look at the picture on the left. 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.