What is the most stressful thing in school? It is probably exams. Exams can put us under a lot of pressure. But some students do better under pressure, while others do not. So why?

It all comes down to dopamine（多巴胺）. Dopamine is a chemical in our body that sends signals（信号）in the brain. It has many important roles: affecting memory, attention and how we learn. Our brains work best when there is a balance of dopamine—not too much or too little. Our brains control dopamine in two ways. It either takes out dopamine quickly, or gradually. Exam success can be connected to how fast dopamine goes back to a balance（平衡）, according to new research from the University of Missouri, reported Yahoo.

What happens when we take an exam? If you become stressed, your brain will start to overload（超载）on dopamine. Scientists found that, the quicker students are able to go back to a balance of dopamine, the quicker the can concentrate（专注）, helping them perform better on a test. However, during a test, students who slowly go back to a balance of dopamine scored 8 percent lower . That’s the reason for a better mark and a worse mark.

But don’t fear, there is good news for every student. The study also found that the more practice you get, the less stressed you’ll be.

Can plants eat people? Probably not, but there are many plants that eat meat. Some of them are big, and they can eat small animals. One famous meat-eating plant is the Venus flytrap(捕蝇草).

The Venus flytrap is a very strange plant. It grows in dry parts of the US. Its leaves are like the pages of a book. They can open and close very quickly.

Inside the leaves, there are three small hairs. If a fly (苍蝇) touches one of the hairs, the leaf closes quickly. The fly cannot get out. After about half an hour, the leaf presses (压) the fly to make it die. Then, the plant covers the fly. Slowly, the plant eats the fly.

Plants are living things that have leaves and roots and grows in earth. Most plants get what they need from the sun, the air, and the ground. In some places, the ground is very poor. It doesn’t have all these important things, especially nitrogen(氮). Animal meat has a lot of nitrogen，so some plants eat it. Let’s hope that some of the bigger plants don’t get the same idea!

Second only to water, tea is one of the most popular drinks in the world. Whether you like it boiling hot, poured over ice, or served with milk and tapioca pearls, there’s a lot to love about tea. But how much do you know about it? Let’s test your knowledge to see if you’re a real tea master.

Although there are thousands of different types of teas, they all come from one plant—Camellia sinensis, a bush native to East Asia. The differences come from where the plants are grown and how their leaves are treated after harvest. Leaves used to make green tea are processed (加工) for instance, they can be lightly-steamed or oven-dried—while those used to make blacktea are left to dry.

It’s true that the British have the reputation (名声) of being great tea lovers, but they don’t drink as much tea as the people of Turkey. A single Turkish citizen uses more than three kilograms of tea leaves per year, which is enough to make over 1,200 cups of tea!

Tea came to England from China in the seventeenth century, but it was so costly that only noble people could afford it. It wasn’t until the first tea shop opened in 1717 that common people got chances to drink tea. By the middle of the eighteenth century, nearly everyone in England was drinking tea.

In the 1700s, many average British folks didn’t have the strong, well-made tea sets that richer people used. Their thinner cups often broke when boiling water was poured inside. Adding milk first helped cool the tea and prevented the cups from breaking.

While tea lovers will argue (争论) endlessly about how to make a great cup, there’s only one rule. The perfect cup of tea is the one that tastes best to you. No matter how you like it, just enjoy!