Scientists think that there has been life on the earth for hundreds of millions of years. However, we haven’t     1     life on any other planets yet.

The earth is a planet and it     2     around the sun. Seven other planets also go around the sun. None of them has an environment like that of the earth, so scientists do not     3     they will find life on them. The sun and its planets are called the solar system, and our solar system is a small part of a much larger group of stars and planets,     4     the Galaxy or the Milky Way. There     5     billions of stars in the Galaxy, and our sun is only one of them.

Scientists     6     many other galaxies in the universe already. They are very far away and their light     7     to travel for many years to reach us. So how large is the universe? It is impossible to imagine.

Scientists have sent spaceships to the planet Mars to take photos. They have even sent spaceships to travel outside the solar system . However, no spaceship has travelled far enough     8     other stars in our Galaxy. Scientists have always asked the questions: With so many stars in the universe, are we alone or is there life in space? Have there been visitors to the earth from other planets? Why has no one     9     with us? We     10     the answers yet.

The moon is our space neighbour. It is a ball of     1     that goes around our home, the Earth. It takes the moon 27 days and eight hours to go around Earth one time. The same side of the moon ways     2     Earth.

The moon is very different from Earth. There is no air, water,     3     wind on the moon. If you visited the moon, you would have to wear a special suit to help you breathe. You would also     4     less on the moon and be able to jump six times higher!

The moon has     5     and dark spots. The bright spots are hills and mountains. The dark spots are places where flying rocks have hit the moon. There are also many flat parts of the moon. These parts look     6     our seas, but you would not be able to sail in the seas of the moon! Do you know why?

Is there intelligent (有智力的) life on other planets? For years, scientists said “no.” or “we don’t know.” But today this is changing. Seth Shostakovitch and Alexandra Barnett are astronomers (天文学家). They believe intelligent life exists (存在)     1     in the universe. They also think we sill soon contact these beings(人；生物).

Why do Shostakovitch and Barnett think intelligent life exists on other planets? The first     2     is time. Scientists believe the universe is about 12 billion years old. “This is     3     enough for other planets to have intelligent life,” says Shostakovitch and Barnett. The second reason is size—the universe is huge. “Tools like the Hubble Telescope (哈勃望远镜) have     4     that there are at least 100 billion galaxies,” says Shostakovitch. “And our galaxy, the Milky Way, has at least 100 billion stars. Some planets going around these stars might be     5     to Earth.”

In the past, it was hard to look for     6     of intelligent life in the universe. But now, powerful telescopes (高倍望远镜) allow scientists to     7     smaller planets—the size of Mars or Earth—in     8     solar systems. These planets might have intelligent life.

Have beings from space already visited Earth? “Probably not,” says Shostakovitch. “It’s a long way away. However, intelligent beings may contact us in other way, such as radio signals (信号). In fact, they may be trying to communicate with us now, but we don’t have the right tools to     9     their messages. However, this is changing. By 2025, we could make contact with other life     10     in our universe and we might help each other.”

Are you an “I person” or an “E person”? This question is widely     1     online. They are part of a popular personality test called the Myers-Briggs Type Indicator, or MBTI. All of the results have four letters, and there     2     16 results in total. “I” stands for “introverted (内向的)” and “E” refers to “extroverted”.

Even if someone is very quiet, many online discussions suggest that an “I” person     3     still act outgoing at times. For example, when an introverted person is with a group of   introverted friends, they might become more social like an “E”person. According to experts, this is called “masking”. That is hiding     4     true personality in some situations. Because human beings want to     5     the sense of belonging by pleasing others.

Using the MBTI result to identify (识别) and describe some     6     personality seems fun. However, I went too far at one time. My sister was making a day-to-day travel plan. She was very     7    . Then I remembered from an article that “P people” don’t like to make or stick to plans. So I said to her, “You don’t seem like a ‘P person’ ”. “Why?” she asked back. “Since when do I need to follow what my personality test tells me to do?” At that moment I     8     I’d taken the result too seriously.

The MBTI personality test may show something you don’t know about yourself and can even be a fun ice-breaker question when meeting new     9     . And that’s all it is—for fun. Knowing someone’s MBTI result doesn’t mean you can     10     know this person. And those four letters of yours don’t define (定义) who you are.

The word moon comes from the Old English wordmonaand shares a root with the word month—    1    the moon revolves around the Earth once a month. While the sun stays the same day after day, the moon    2    every night, allowing ancient people to know the days, months and seasons.

Many of the names for the moon have    3    to do with traditions of ecology and ways of life. You might    4    some of them.

1. Blue moon

Today, the blue moon is the second full moon    5    a calendar month. It’s unusual for a blue moon to come around—it only appears once every 2.7    6    . So the expression “once in a blue moon” means “very rarely or almost    7    ”. If something happens once in a blue moon, it happens very infrequently.

2. Harvest moon

The word harvest comes from the Old English wordhaefestwhich referred to the autumn season. In the mid 1200s, harvest became much    8    to the meaning of today—the gathering of crops. In China, the Mid-Autumn    9    is celebrated during the harvest moon.

3. Cold moon

In most parts of the United States, January is cold. So it makes sense to    10    January with the cold moon. It wasn’t until the early 1800s that English language texts showed “cold moon” in relation to the January full moon.

Think about different ways that people use the wind. We can use it to fly a kite or to sail a boat.

Windmills began to be used in seventeen century BC. At first, people used windmills to grind (磨碎) wheat     1     flour and get water out of the deep underground.

When Benjamin Franking found electricity in the late 1800s, people began to use it in many different ways, like electric lights and radios. However, when electricity was everywhere by the 1940s, windmills were     2     used. During the 1970s, people started worrying about the     3     when coal and gas are burned to make electricity. People also realized that there were not enough coal and gas for us to use. Then people started to reuse windmills, though it means     4     costs.

The universe is very big. But how large is the universe? It is impossible     1     how large the universe is.

But we know the earth is our home. It is a planet and it     2     around the sun. The moon goes around the earth. There are seven other planets go around the sun. The sun and its planets are a system     3     the solar system. So far, some astronauts     4     to the moon. Some scientists     5     many spaceships to some other planets. But we haven’t     6     life on other planets, because none of them     7     an environment like the earth.

Scientists have also found many other galaxies in the universe. But they are very far away, so no spaceship has travelled far enough     8     them. Is there any life out of the solar system? Have there been visitors to the earth from other planets? I think there is still a long way     9     to know that. When I grow up, I     10     an astronaut and work for China’s space station.