Have you ever wondered how we know the things that we know？ How do we know， for example， that the stars are really huge balls of fire like the Sun and very far away？ And how do we know that the Earth is a smaller ball turning round one of those stars， the Sun？

The key to these questions is "evidence"， which means the facts， signs or objects that make you believe something is true．

Sometimes evidence means actually（实际地） seeing（or hearing， feelings， smelling …） that something is true． Astronauts have travelled far enough from the Earth to see with their own eyes that it is round． Sometimes our eyes need help． The "evening star" looks like a bright twinkle in the sky， but with a telescope（望远镜） you can see that it is a beautiful ball． Something that you learn by direct seeing（or hearing or feeling …） is called an observation．

Often evidence isn't just observation on its own， but observation always hides at the back of it． If there's been a murder， often nobody（except the murderer and the dead person!） actually observed it． But detectives can gather together lots of other observations which may all point towards the suspect． If a person's fingerprints match those found on a knife， this is evidence that he touched it． It doesn't prove that he did the murder， but it can help when it's joined up with lots of other evidence．

Prediction（预测） helps to look for evidence． Scientists make a guess about what might be true． For example， if the world is really round， we can predict that any of us， going on and on in the same direction， should eventually find ourselves back where we started．

People sometimes say that you must believe in feelings deep inside， but not all the inside feelings are real evidence．

What can we do about all this？ When somebody tells you something that sounds possible， think to yourself： "Is there any evidence for that？" And， next time somebody tells you that something is true， why not say to them： "What kind of evidence is there for that？" Remember， always think carefully before you believe a word．

32． Which of the following is TRUE according to the passage？　　

A： What you see directly is real evidence．

B： Prediction helps to prove something if it is true．

C： People should always believe their inside feelings．

D： Astronauts find the Earth is round with a telescope．

33． Why does the writer use the example of a detective in Paragraph 4？　　

A： To explain what prediction is．

B： To tell what observation is called．

C： To introduce how detectives work．

D： To prove evidence is not just observation．

34． The underlined word "eventually" in Paragraph 5means　　．

A： finally

B： probably

C： completely

D： luckily

35． What's the best title of the passage？　　

A： Evidence speaks

B： Scientists make predictions

C： Inside feelings help get ideas

D： Observation offers the facts