It is hard to be a farmer. Cold weather can kill your crops. Bugs can eat your crops. Weeds(杂草) can hurt your crops. Your crops may need more rain than they get. Fruits and vegetables can go bad before they are sold. Some people say farmers can fix all of this with GM food.

What is GM food? All living things have DNA. DNA tells living things how to grow. These days, people can change the DNA that tells food how to grow. When people change the DNA of food, it is called GM food.

Some GM food can grow in cold weather. GM food can stop bugs from eating it. GM fruits and vegetables can stay good longer. One day, GM food may be able to grow in dry land in Africa. It will feed people who do not have much food.

But there is a lot we do not know about GM food. Will GM companies help poor people grow food? Or do GM companies just want to get rich? Does GM food kill bugs we need, like butterflies? Does GM food make birds sick? Does GM food make people sick? We do not know. There have not been many tests on GM food.

Do you think farmers should grow GM food?

You probably think the music that your parents like is old and boring, and the songs on your playlist are much cooler. 【小题1】 So it is likely that your own musical preference will follow a similar way to your parents’.

Researchers at the University of Cambridge got data (数据) from more than 250,000 people over the past 10 years. 【小题2】 There are three musical periods (时期): “exciting”, “popular” and “sophisticated (高雅时髦的)”.

The first period comes in the teenage years. 【小题3】 But as people move into early adulthood, they hope to build close relationships with others. As a result, they become fonder of popular music, such as pop and R&B, which are usually danceable. When middle age comes, things have settled down (安定下来) for most people. 【小题4】 For example, they prefer jazz and classical music, as well as catchy music like country music and blues. Because they need relaxing and emotive (激起感情的) music under the strong pressure of life.

But you must be thinking: “Aren’t there old people who are still into rock music?” Of course there are. But a research member explained that their reasons for listening to rock music may be wanting to remind themselves of their youth at that time.

What do you do when you feel unhappy? Do you listen to music? Do you talk to a friend?

Maybe next time you feel sad, you should try going outside if it is sunny. Doctors know that how much sunlight we get can change how we feel. Scientists learned this by interviewing (采访) people who live in different parts of the world. In the far north, in Alaska of Finland, for example, the days are very short in winter. People living in these places say that they are unhappy in winter. The reason is the amount (数量) of sunlight these people get each day. Sunlight changes the chemicals (化学物) in our bodies, and these chemicals can change the way we feel. Several hours of strong sunlight can help your body make the chemicals. These chemicals can make us feel happy.

Another way to feel happier is to get some exercise. Just like sunlight, regular (规律的) exercise helps our bodies make certain chemicals, which make us feel happier. What’s more, exercise helps people sleep better. Enough sleep often makes people feel happy. Exercise also helps you get rid of stress (压力). When you are angry or upset about something, exercise is a way to get those bad feelings out of you.