Have you ever had lucid (清醒的) dreams? Recent studies suggest that the number of people having them is on the rise. Someone having a lucid dream realizes they are dreaming and may from then on" direct" the action, or they may simply " watch" the dream unfold. The sense of awareness (知道) makes it different from a dream that is simply very lively and true to life. And although the description may seem strange, the process is far from alien to many of us.

Studies suggest that the number of people in the Western world experiencing lucid dreams, which happen once in a while, has risen by between 10 and 40 per cent since the 1980s. Today, they are so common that about one in eight of us will have one in our lives. But still, little is known about what causes them or what is behind the rise.

Research carried out at the respected Harvard University in the US shows that the brain is working hard during lucid dreams. In fact, the level of the mental (精神

的) activity in some parts of the brain is similar to that of a person who is awake. Lucid dreamers seem to share certain personal characters. For example, in general they are quite creative. They are also good at digging deep into problems and going out of their way to solve them. Furthermore, they always believe in personal responsibility rather than letting society carry the can.

Our nightmares (噩梦) may show our waking worries, with the five most common ones-- falling, being run after, feeling disabled, being late and the death of a loved one. Men are more likely to have nightmares about fights or being fired while hair and tooth loss appear more in women's nightmares-perhaps showing worries about losing their looks. Research has also found that women have more nightmares than men. Their dreams are also scarier and more unforgettable.

Li Hua: Hi, Sally! Welcome to China. {#blank#}1{#/blank#}

Sally: Of course I did. I went to the West Lake in Hangzhou last summer. 

Li Hua: Really? {#blank#}2{#/blank#}

Sally: Yes. I went with my grandparents. They like China a lot. 

Li Hua: {#blank#}3{#/blank#}

Sally: We just stayed there for three days but we had a great time. 

Li Hua: {#blank#}4{#/blank#}

Sally: There was lots of delicious food to eat. Everything tasted really good!

Li Hua: Sounds great. So where would you like to go this time?

Sally: Hong Kong, I think. {#blank#}5{#/blank#}

Li Hua: You're right. Hong Kong is a great place for you to buy many things. 

When you have a cold drink in summer, you may get a toothache. If eating ice cream or drinking cold drinks make your eh hurt, it could be a kind of protein(蛋白质) called TRPC5 at work.

A new study which came out on March 26 answered a long-lasting question about our teeth—why do cold food and drinks make our teeth hurt? Actually, when you feel a toothache, it's because a kind of protein feels a drop in temperature and sounds an alarm to your brain. The research team found this protein 15 years ago. But they didn't know where in the body it felt the temperature. Now they know it—it's in a kind of tooth cell.

David Clapham from the research team explained how our teeth sensed cold. When someone is eating ice cream, for example, cells with TRPC5 in teeth feel a change in temperature and send a signal to the brain. As a result, you will be sensitive to the cold food and feel pains. I is also found that here will be more TRPC5 if your teeth are worn away(磨损), so a great way to prevent a toothache is to treat it gently. If you don't know what to do, the following tips can help you out;

●Don't brush your teeth too hard. Brush up and down to keep them clean and strong.

●Say goodbye to soda and sticky candy, because they can wear your teeth away.

●Stop grinding(磨) your teeth. That will make your teeth more sensitive(敏感的) to coldness.

If all of these don't work, go to the dentist!

 There are millions of teenagers using social media every day. Although some people think social media is a positive thing, many are worried about the negative influences it can have on young people.

 Many teenagers agree that social media helps them stay connected to their friends and make new friends from around the world. More and more teenagers are willing to share their life and thoughts online. Thanks to advances in technology, how teenagers make friends and communicate with each other has changed greatly.

 However, social media also has many disadvantages. One of them is that some parents believe social media makes it harder for families to spend time together. They say that things on the Net seem super appealing, and that their kids can't take their eyes off the screen. As a result, teenagers pay no attention to the rest of their family.

 Another serious problem is that social media makes bullies(霸凌者) easier to reach their goals. A great many people have experienced cyberbullying - - bullying that takes place online. So how can teenagers protect themselves if the cyberbullying has taken place? Gwen Taylor, an expert from a charity, which works to end online bullying suggests, "The first thing to do is to tell a trusted adult about what is going on. " "If someone posts content that frightens you, you can report it to the social media platform. You'd better keep the screenshot(屏幕截图) of the behavior because this will help you to report it and help others to help you, "says Taylor.

 Perhaps the more effective way is to try to be a good digital citizen. How you act online is just as important as how others treat you. Good digital citizens use online spaces positively, which means treating everybody online with kindness and respect. Respect other people's feelings and don't be mean (刻薄的) . "If you have shared something you shouldn't have, it's never too late to say sorry and fix the situation, such as taking the post down. If you notice somebody is being cyberbullied, consider reporting it and getting in touch with the person being treated badly to make sure he is OK, "Taylor advises.

Can 13-year-olds do something to change the world? Cris Kesz Valdez, 13, from the Philippines believes so.

At the age of 7, Valdez set up an organization to give homeless kids things like slippers and toothbrushes. So far he has helped more than 10,000 children improve their lives in his hometown.

Valdez won the 2012 International Children's Peace Prize on September 19, 2012.

"My motto is ‘we can change the world one heart at a time,' " Valdez said at the award ceremony.

In fact, Valdez is a homeless kid himself. He looked for food from trash, lived on the streets and slept in a public cemetery for most of his childhood. His parents didn't care about him and often beat him. Valdez said he felt he was living in "darkness" at that time.

But this "darkness" didn't turn him into a dark person. Valdez got help from community workers. On his first birthday party, at the age of 7, Valdez decided what he wanted most was to help other children who were still living on the streets.

"I didn't have a lot of money, but I had a lot of love to give," Valdez explained.

That day was the birth of the organization, Championing Community Children. Since then, Valdez and his friends visit homeless children and hand out bags with slippers, toys and even candy. They nurse their wounds, teach them about their rights and offer them hope.

"I want children on the streets to get the same chance as I have," he said.