What is the sky? How high is it? What color is it? What birds can live above it? These questions are difficult to answer, aren't they? In fact, the sky has no color. Then why does the sky look blue?

    We know that there is air around the world. When planes fly, they need air to lift their wings. Planes can't fly very high. That is because the air gets thinner when they go higher. The same will happen to us if we go high enough. If we go up about 1,200 kilometers from the earth, we'll find no air there. Some birds can fly into the sky as high as a plane, but they cannot fly or live without air.

    Looking up above us, you will see the blue sky with white clouds. It is usually light blue. The color would be bluer when you see on the top of a high mountain. And you will see fewer clouds in the sky between you and the sun. Sometimes the sky doesn't look blue. When the sun rises and falls, you will see red, orange and other colors in the sky, such are the most beautiful moments of the day.

    Who can see the colors of the sky high above the earth? The astronauts! They can see those beautiful colors of the sky from the outer space. However, before flying into the outer space, they sit in a spaceship high above the earth and there is no air at all. The sky would be that dark and its color would be black.

    Now you may understand that we see colors because the air scatters (使散射) the sunlight. Light travels through the air. Without air there would be no colors.

    Many years ago, most of our earth was covered with blocks (块) of ice. These ice blocks were as tall as high buildings in modern cities. Most of the ice was in the northern part of the world. Then the ice blocks started to move south. Cold and rain came with the ice. Animals had to move. At last, the ice began to melt (融化). After half a million years, most of it melted. More than half of the earth became covered with water. The climate became much warmer. Things began to grow. The earth began to look the way in which it looks today.

House fires cause many deaths each year and a large number of these fires are unfortunately set by children.{#blank#}1{#/blank#}Kids must understand that they'd better not play with fire. You should keep matches and lighters out of their reach.

{#blank#}2{#/blank#} The main job of such an alarm is to protect you while you're asleep. You should have a smoke alarm outside each bedroom and on each floor of your home. You ought to have two plans for getting out of your house if there is a fire and practise these plans in the dark with your family.

A smoke alarm warns you of the danger. {#blank#}3{#/blank#}Take action immediately. When you come to a closed door, check it with the back of your hand. If it feels hot, there may be smoke or fire behind the door, so take care. Once you are out of your house, call the fire department from a neighbor's house. If a family member or a pet is caught inside, you shouldn't go back in. Firemen know how to perform rescues safely.

{#blank#}4{#/blank#} Change the batteries at least once a year. You should use the test button each month to see if the alarm and batteries are still working. A smoke alarm lasts about ten years. You ought to change it even if it seems to be working.

Chinese tourists flock(涌入) to Morocco(摩洛哥) during Spring Festival

In the Chinese restaurant of Chefchaouen, one of the, top tourist attractions(旅游景点) in Morocco, an area of less than 100 square meters was full of more than a hundred Chinese tourists, with a lot more waiting outside, during the Chinese Spring Festival.

"Boss, can I have my Kung-Pao Chicken now?" "Boss, is my beef noodles ready?" Some visitors were not patient cough to wait long for their ordered foods. Restaurant owner said that during the Spring Festival, beer business was much better than usual.

Another Chinese restaurant owner in Fes, Morocco's central city, had the same experience. The waiters said during the Spring Festival, a large number of Chinese tourists waited in lines for meals every day.

In the southem Moroccan town of Marrakech, tourist buses full of Chinese tourists can be found everywhere during the Spring Festival.

In Majorelle Garden, a famous tourist attraction, two girls from Ningbo, a city in East China's Zhejiang province, said they chose Morocco as their Spring Festival travel place to taste the country's special food.

Morocco's Minister of Tourism Mohamed Sajid said it hopes to attract (吸引) 500,000 Chinese tourists each year by 2020.

Sajid also said Morocco is working to improve hotels, transports and tourist reception. He said direct flights(直达航班) between Morocco and China are being discussed, which is one of the key factors to attract Chinese tourists.

阅读下列短文, 从下面每个小题的A、B、C、D四个选项中选出最佳选项。

A study conducted by the University of Leeds in the United Kingdom suggest that watching cute animals may lead to a reduction in stress and anxiety.

The study examined how watching images and videos of cute animals for 30 minutes affects blood pressure, heart rate(心率) and anxiety. In December 2019, 19 people, including 15 students, joined in the study.

"There were some kittens, there was puppies, there were baby gorillas, there were quokkas —cute creatures found in Western Australia, are often referred to as 'the world's most cheerful animals'." Dr. Andrea Utley, a professor at the University of Leeds told CNN. The study was timed during winter exams, a time when stress is at an especially high level for students, according to Utley.

 The study recorded that the average blood pressure dropped from 136/88 to 115/71, which the study pointed out is "within ideal blood pressure range." Average(平均的) heart rates were lowered to 67.4 bpm, a reduction of 6.5%. Anxiety rates also went down by 35%.

"I was quite pleasantly surprised that during the session, every single measure for every single participant dropped some — heart rate reduced, blood pressure reduced," Utley said. "When they left, they filled the questionnaire(调查问卷) in again and showed that they were feeling less worried."

When questioning the participants, the study found that most preferred video clips over still images, particularly of animals interacting with humans.

Do you have trouble trying to create the next big idea?

Sometimes the answer isn't to just force an idea out of your mind.

Instead, you might want to try sitting back, relaxing and letting your mind wander（走神）. Yes, you heard that correctly. If you are in need of a new idea, try daydreaming.

Daydreams allow your mind to run freely and even increase productivity in some cases. Daydreaming develops creativity which is why you have an ah-ha moment and sudden insight（领悟） about a situation. Daydreaming allows you to uncover thoughts and ideas you did not realize you even had and get the thoughts hidden under the surface.

Researchers from the University of California, Santa Barbara, found a connection between daydreaming and creative problem-solving. Their study includes making participants first do an "unusual-use task". They had to try to come up with as many different ways to use an object as they could.

Then, the participants choose to do one of the following four things before doing the "unusual-use task" again; complete a difficult task, complete an easy task, take a 12-minute break, or skip a 12-minute break and move right on to the task exercise again.

Surprisingly, the group that performed best was the one that completed the easy task. Many participants reported that they were daydreaming while performing the easy task. So the researchers believed that this daydreaming might have helped unlock their creativity.

But how could daydreaming help the brain come up with creative ways? The answer is something known as "unconscious thought". Even when you are not actively working to solve a problem, it is still in the back of your mind. Your brain is still thinking about the problem, but in a way that you are unaware of.

When you daydream, your mind is allowed to think in ways it normally would not. Because it is free of control, it can create completely new and out-of-the-box ideas.

Great ideas never come easily, but that does not mean you always have to work hard to get them. Feel free to do what you want and let your mind wander.