We always think that it's OK for us to leave our plants home during our vacation as plants won't scream like pets, right?

    A recent study done by a group of scientists at the Tel Aviv University has discovered that some plants will scream when they are under stress.

    The research was carried out on tomato plants and tobacco plants by cutting their stems (茎) and depriving (剥夺) them of water. A microphone was placed 10cm away from them. When their stems were cut, the plants started "screaming" between 20 and 100 kilohertz, and the scientists guess that this scream is probably meant to warn other plants nearby.

    When the tomato plants' stems were cut, 25 ultrasonic (超声的) pain sounds were recorded in an hour, and at the same time, 15 ultrasonic pain sounds were recorded from the tobacco plants. When they were deprived of water, the tomato plants recorded even more pain sounds with 35 pain sounds in an hour while the tobacco plants recorded about 11 pain sounds.

    The plants also acted differently to different kinds of stresses. For example, the tobacco plants gave out a stronger "scream" when they were deprived of water than when their stems were cut. But plants that were in no immediate (立刻的) danger gave out less than one ultrasonic sound per hour.

    The group of scientists said that plants are not as quiet as we had always thought, but in fact their voices are so high-pitched that we just can't hear them.

    Last year, another study has found out that plants feel pain when they are touched or hurt and they will give off a terrible smell.

    Today more and more children wear glasses before going to middle school. They keep their eyes watching TV or playing computer games for a long time. Eyes are the windows of our hearts (心). We use our eyes to see everything around us, so we should know how to protect our eyes.

    Love our eyes. When we open (睁开) our eyes every day, we can see the lovely friends and parents, beautiful flowers and green trees. If our eyes don't work, how can we see the world. In our eyes, everything and everywhere is dark. It's like a house with no light (光). How important our eyes are!

    Relax our eyes. First, stop to relax 30 minutes when using the computer for an hour or two. Next, remember to do eye exercises every day. Then, looking at green trees also helps a lot. In these ways, our eyes will feel relaxed.

    Have good habits. When writing homework and reading, it is important to keep a distance (距离) of 30 cm between your eyes and books. Remember to use our eyes in a right way. Don't read in bed or on a moving bus. Eat something healthy for eyes, such as carrots, fish and eggs.

    Follow my advice (建议) and get good habits. It's time to say goodbye to thick (厚的) glasses.

You will probably know the feeling—it is time for school, but your eyes are only half-open. Your arms and legs are heavy and your brain is still asleep. So what can you do to stay awake when you are tired? {#blank#}1{#/blank#} 

Eat breakfast

Breakfast is the most important meal of the day, but it is also the easiest to skip（省略）. Start your day off with a healthy breakfast. {#blank#}2{#/blank#} They can keep you from feeling hungry and tired in the morning. 

Use water

When you are tired, water is your friend. {#blank#}3{#/blank#} It is even better than drinking lots of coffee. Coffee is fine in the morning, but it is best to drink water after lunch to make sure you can get to sleep. 

Get moving

 {#blank#}4{#/blank#} A few minutes of physical activity can improve oxygen circulation（氧循环）and keep your body active. It doesn't need to be anything difficult. A few push-ups and a short walk may be a great help. 

However, there is still something that you can't do when you are tired. {#blank#}5{#/blank#} Besides, if you find you are often feeling tired and you are not sure why, it is a good idea to speak to a doctor. 

 {#blank#}1{#/blank#} Can you imagine a sea of sand three times bigger than India? This is the Sahara Desert, the largest desert in the world. It covers 11 countries in North Africa and is over 9 million square kilometers. 

 {#blank#}2{#/blank#} In the Sahara, temperatures are very different during the day and night. It is much hotter during the day than at night. Because of the extreme 极端的) temperature in the desert, it is a very difficult place to survive(幸存). Marco Rivera, our survival expert, has some tips. 

 {#blank#}3{#/blank#} Take warm clothes and a blanket. You will need a hat, long trousers and a thick sweater to keep you warm at night. During the day, cover your body, head and face. Clothes protect you from the sun and keep water in your body. You will also need a warm blanket at night. It can get cold rapidly (迅速地). When the temperature drops, it can make you feel even colder. 

 {#blank#}4{#/blank#} Try to drink some water at least once an hour. You need your water to last as long as possible. Drink only when you need. If you eat, you will get thirsty and your water will run out soon. You can eat a little to stop you from feeling very hungry. Eat small amount of food slowly. 

 {#blank#}5{#/blank#} It's important to stay out of the sun during the day. Make a hole under your car and lie there. This will keep you cool and help you sleep. Find a warm place to sleep at night. A small place near a tree or a rock will be the warmest. But be careful before you decide where to sleep. Dangerous animals like snakes also like to sleep in these places. Look carefully for animals before you lie down. 

(a)根据短文内容，从方框中选出每段的主旨大意。

(b)根据短文内容，补全下面的表格。每空一词。

Recently, researchers have found that dolphins know their own names much like people. Dolphins talk to one another with whistles (口哨) and calls. Scientists have known that the animals also use unusual whistles to name each other. They had thought that dolphins only heard each other's voices. However, the scientists didn't know that dolphins listen for their names too.

To test this idea, the researchers caught 14 dolphins and recorded their name calls. The scientists then copied each dolphin's voice. When the changed recordings were played, the dolphins replied strongly to the names of their relatives and group members. They paid no attention to the names of dolphins they did not know.

Dolphins live in large groups that grow and change. Each dolphin's unusual whistle helps it quickly find a friend or a family member, or call for help. Understanding their calls requires learning. It's a skill that's seen in very few animals, which include humans and elephants.

Elephants, for example, communicate with sound. Their sounds can be heard by other elephants miles away. Dolphins, too, communicate with each other by making sounds like this. Elephants also communicate by moving their head, feet and trunk (象鼻). In much the same way, dolphins communicate by their movements. They often touch each other to express friendship.

Unlike dolphins, elephants also communicate by their great sense of smell. They can recognize other elephants by the smells they have.

Why do dolphins and elephants share the gift of communication? Scientists think it may be because they are social and smart animals. Both have strong family relationship. Now, whether they also have nicknames(绰号) is another question!

Have you ever been to Ireland? If not, you should think of spending a vacation there. The Republic of Ireland stands in the south of the island. There are about 3, 470, 000 people in the country and the weather is quite wet but warm. Falls of snow in Ireland are most unusual. 

Ireland is full of interesting things to do. You'll find restaurants and café everywhere. Most of them have a long list（清单） of Irish food and drinks. After your meal, you can take a walk along the shore（岸）. The countryside is good for horse riding. Other sports you may want to do are sailing, boating, swimming, fishing and golfing. Ireland is famous for its theaters and festivals. So, why don't you stay longer for a party or a concert? 

The Irish people are kind and friendly. From mountains to beaches you will find people ready to stop and talk about the weather, the local geography or history and maybe about what you should see next. The Irish people have kept their own culture of music and literature（文学） well. Different areas have different kinds of music. In towns and villages people get together in the evening to sing and play music. They also get together to read their own poems to each other. Meeting such people is really fun, isn't it?