Today there are 6 billion people on the earth. By the year 2050 there may be 12.5 billion. There are a lot of people to feed. We need more food.

One way to produce more food is by growing stronger plants. For thousands of years，farmers have made plants better. Every season, they pick the best plants for the next season. It works very slowly. Since 1983, scientists have been able to change plants more quickly by changing their genetic material (遗传物质). Foods from plants grown in this way are called genetically modified foods (转基因食品), or GM foods.

    By changing the genetic material of a plant, it is possible to make new plants. They make plants which are strong against plant diseases. They can also help with our diseases: a kind of rice is being prepared, for example, which stops people from becoming blind.

    Rich countries produce GM foods because they are easy to grow and bring in more money. Poor countries are interested in them because they help produce more food.

    GM plants are not natural. No one knows how good or bad they are. Making GM foods is only one way of feeding people in 2050. There are strong feelings against them, because they are unnatural. They may feed people, and then hurt them or their children later. But, both rich and poor countries are very interested in their use, and they are not going to go away. In 2050, we may think differently about them.

    Pollution inside homes and other buildings kills more than 4 million people each year．Many people die as a result of breathing smoke or from cooking over wood﹣powered of coal﹣powered stoves．

    One way to reduce the number of deaths is through cooking equipment powered by the sun．Crosby Menzies，a solar power expert in a South African company，described his latest solar cooker called the“Sol.4”，”It is four square meters of mirrors，six to eight meters in length．It is quite a large cooler．”

    The“Sol.4”works by reflecting （反射）light from the sun off large mirrors．The mirrors direct （把…对准）the light at a cooking pan．Then the light heats the pan with solar energy．Within two minutes，the pan is hot enough to cook sausages and onions．In just four minutes，water can be boiled．That is as fast as cooking with natural gas or electricity．

    The cooker is also much“friendlier”than other models because people do not have to stand in the sun to use it．And people can prepare meals without having to collect firewood or spend money on coal．Suchindividualswould be less likely to have breathing illnesses from harmful smoke．

    At present，the cooker only works when the sun is shining．But engineers are working on a way to make it work without sunlight．

    Each cooker costs about $2000，which is a large amount of money for most Africans．To solve that problem，Crosby Menzies has crated a non﹣governmental organization called solar Cookers for Africa．It plans to raise money through donations to provide poor people with solar cooking equipment．

    How do animals communicate (交流) with each other? They have special "languages". In fact, they are using signals (信号). Different signals have different meanings.

    For example, when a bee (蜜蜂) finds food somewhere, it flies home quickly. It can't speak, but it can tell others by dancing. Other bees will know where and how far the food is.

    Some animals show their feelings by making sounds. For example, when a dog is angry, it barks (吠). At this time, you'd better stay away from it. Birds can make several sounds to show different meanings. Sometimes we humans show feelings by making sounds instead of by speaking. For example, when we feel painful (疼痛的), we cry "Oh!" or“Ouch!".

    We humans have languages and words. We can communicate face to face by speaking. We can write down what happened in order to remember clearly. We can also send (寄) messages to people far away. But animals can't.

Once a man walked to India where he had never been before. When he got there, he saw many kinds of fruits. But most were expensive. The man saw a big basket of red, long fruit. He thought it must be sour and sweet. 

He went up and asked, " How much per kilo?"And the shopkeeper said, "Two rupees(卢比). "

Two rupees in India is nothing. And it was the cheapest in the shop. So he bought a kilogram and started eating it. But after he ate some, his eyes watered, his mouth watered and burned, and his face became red. He even coughed while eating. 

But he still ate the fruit! Some locals who were looking at him shook their heads and said, "You're crazy, man. It's chilly! You can't eat so much! People use it as spice(调味品), but only a little bit to put into food for taste. They're not fruit!" But the man said, . "No, I can't stop! I can't waste my money. "

Do you think that man was stupid? In fact, we sometimes do a lot of things like that. We put money, time or effort into a relationship, business or job. Even though over a long time it won't work, and we know things will never change in the future, we still go on just because of the things we've put in. like the man. 

So even if you've lost something, let it go and move on. That's better than keeping losing. 

Here are three students.They are talking about sports.

My baby graduated last week. Waiting for the ceremony to begin, I took a photo and posted it on Facebook with words "I'm teary. " However, autocorrect (自动更正) changed my words to "I'm ready. " For a minute I was unhappy. But the next minute I was cheering the handsome man, as he walked straight with a big smile to the headmaster. My heart was filled with pride, and I began to wonder if autocorrect had known something. 

The idea of "empty nest" is often connected with sadness, but the truth is that birds don't have a problem with it. Birds' parents encourage their children to leave the nest as soon as possible, while continuing to provide support. That sounds right to me. The fact that my kid is brave enough to go out on his own means I did my job well. And I should have the rewards. 

So, I started with a hot bath at 6:00 p. m. I enjoyed it for over an hour, and then went out to do some running. Back home then, I cooked salmon -my favourite fish but my boy disliked its smell. Later, in the evening, I didn't have to tell anyone to turn off his computer and get some sleep. But at midnight, I missed my boy a little bit more. 

The next morning, I went for a walk. Was I a terrible mother to live in the house by myself? Then I remembered: my kid flew because I taught him to fly. If I'm happy to be drinking coffee as I write this, it's not about not loving my boy but about finding his independence when he's away. It's about realizing that when your smartphone autocorrects "teary" to "ready", you should take note.