How much do you know about Earth-the planet that we live on? Our knowledge of Earth has been developing since ancient times. However, many puzzles about Earth remain unsolved. Live Science has published a list of the eight biggest mysteries about Earth. Let's look at some of them.

Where did water come from?

When it first came into being 4.5 billion years ago, Earth was a dry rock. So where did all of our water come from? Scientists think that it might have arrived in the form of ice by an asteroid(小行星) from outer space that hit our planet. But this theory has not been confirmed because there is very little related evidence(相关证据)to be studied.

What's in the core(地核)?

Scientists used to study meteorites(陨石)as small examples of Earth, believing that Earth's core was made of iron and nickel(镍). However, a later study in the 1950s proved this way to be wrong because it found that Earth would be too light to provide gravity if its core contained only iron and nickel. Today, scientists continue to bring forward different theories, but none have been confirmed.

How was the Moon born?

Scientists have found that the chemical compositions(成分)of Earth and the Moon are very similar. That suggests that the Moon actually came from Earth. For example, it could be a piece of Earth that separated when Earth hit another planet. It is also possible that when Earth first came into being, it spun(旋转)very fast and threw off enough molten(熔化的)rock to later from the Moon.

1.What's the story mainly about?

A.How Earth came into being. B.Where Earth's water came from.

C.How the Moon was formed. D.Unexplained mysteries about Earth.

2.What do we know about where water may come from?

A.Earth's water may come from ice that melted 4.5 billion years ago.

B.Earth's water may come from a small planet that hit Earth.

C.We don't know where water came from.

D.There is lots of evidence that tells us where water came from.

3.What does the underlined phrase "bring forward" in Paragraph 5 probably mean?

A.Check. B.Raise. C.Improve. D.Receive.

4.Which of the following is TURE according to the passage?

A.Scientists believed Earth's core was made of meteorites.

B.A study in the 1950s proved that Earth's core is made of iron and nickel.

C.The Moon and Earth are made of similar materials.

D.Three possibilities of where the Moon came from are mentioned.

Helping others is a great thing to do. You can learn new things and have fun. There are many ways of helping others in your community. You can help people, animals or the environment(环境). It can make you feel good too! How can you help?

Charities (慈善机构) are organizations that help others, for example, UNICEF or the World Wildlife Fund. You can help charities by giving your time, giving money or giving things that you own .You can also help people or places you know.

Volunteering

Volunteering is when you give your time to help others .It’s something which you do not have to do or for which you will not be paid. Some ways of volunteering are:

•visiting old people to talk to them or help them.

•walking dogs at an Animal Helper.

•cleaning up a park.

Fundraising

Fundraising is when you collect money to help others. Ways of fundraising are:

•making cakes or biscuits to sell.

•doing a sponsored (赞助) activity. For example, family and friends give you money if you finish a long walk.

Donating

Donating is when you give your things or money to help others. Some ways of donating are:

•giving your old toys or clothes to a charity that helps sick children or poor people.

•giving your old books to a library.

•giving your money to a charity.

So, what can you do to help others?

1.You’ll _______when you help other people.

A.feel uncomfortable B.have a great job

C.feel good D.have a hard time

2.How many ways of volunteering are mentioned in the article?

A.Two B.Three C.Four D.Five

3.The underlined word “fundraising” means “ _______” in Chinese.

A.募款活动 B.慰问活动 C.志愿活动 D.捐物活动

4.Which of the following is a good way to raise money for a charity?

A.Visiting a sick child. B.Doing a sponsored walk.

C.Cleaning up a library. D.Talking with old people.

5.Which of the following is a way of donating?

A.Cleaning up a park. B.Giving your old computer to a charity.

C.Taking care of sick people in hospital. D.Making pancakes or sandwiches to sell.

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