Can you remember a morning when you’ve woken up to the ring of your alarm clock and wished you could stay in bed? You haven’t slept well, your hair is a mess. Worse, you can’t stop yawning. Yawning is universal to humans and many animals. Cats, dogs and fish yawn just like humans do! Yawning is an involuntary(无意识的,不自觉的) action during which you open your mouth and breathe deeply. The average duration of a yawn is about 6 seconds.
The purpose and cause of yawning are still a mystery. Scientists are not sure what causes a yawn. People yawn when they are tired or bored, but they also yawn when they aren’t. There are many ideas explaining why we yawn.
One idea is that yawning is a way for the body to become more alert by taking in more oxygen. A yawn increases the heart rate, forces carbon dioxide out of the lungs and blood stream, and brings oxygen to the brain. But one study showed that volunteers given a lot of oxygen did not yawn any less than before, while those given a lot of carbon dioxide did not yawn more.
Another idea is that early humans used yawning as a form of communication. If one decided it was time to sleep, they would tell the others by yawning and they would do it in return to show they agreed.
A third explanation comes from psychology professor Gordon Gallup of University at Albany in New York. He said that as people yawn, they cool off their brains. “Brains are like computers.” he said. “They only operate efficiently and effectively when they’re cool. Many things connected to yawning, like being tired, make the brain hot, and yawning can reduce the heat.”
Scientists have sent people into space, and created terrible nuclear weapons, but there are lots of seemingly simple things, such as why we yawn, or hiccup（打嗝）, that they can’t figure out. Next time you are in class in the morning, let out a big yawn and watch to see how many of your classmates yawn in response!
【小题1】What’s the purpose of the description of how bad you may feel when you’re woken up in the morning?

A．To explain why humans yawn.

B．To explain how humans start yawning.

C．To lead into the topic of yawning.

D．To complain about being woken up by the clock.

【小题2】Which is not among the possible reasons for yawning mentioned in the passage?

A．A way to show that you feel hot.

B．A way to get rid of carbon dioxide.

C．A way to cool off your brain.

D．A way to communicate.

【小题3】In which situation are you likely to yawn?

A．When you feel frustrated.

B．The weather is hot.

C．Someone else yawns near you.

D．When you breathe in a lot of carbon dioxide.

【小题4】What can we learn from the passage?

A．The real reason why humans and most animals yawn.

B．Hiccups are an involuntary human action similar to yawns.

C．The more an action can be studied, the easier it is to research.

D．Finding out why humans yawn should be easier than sending people into space.

  Things similar continuously happened in Haiti and Chile．Thousands of people were

buried in the earthquake and lost their fives．What if we could have warned them? People are always trying hard to find a way of preventing building collapsing(坍塌)．Better materials and technology help，but are not a solution．Just like humans，a building has its own life circle from  “birth” to “death”．If we know when a building is going to collapse，we can repair it in advance or get out before it falls．

    Now, scientists at the University of Illinois have developed a material that turns red before it breaks．The invention could be used in things like climbing ropes，or bridge supports．The secret behind the color-changing material is a type of molecule(分子)．A molecule is a group of atoms held together by chemical bonds(化学键)．Imagine you and your friends standing in a circle，holding hands．Each person stands for one atom，your hands represent the bonds，and the entire circle represents a molecule．If one person lets go of his or her hands，the molecule changes color．The research team put the molecule into a soft material．When the researchers stretched(拉长) the material：it turned bright red a few seconds before it broke into two pieces．

When they repeatedly stretched and relaxed the material，without breaking it，it only turned a little red．

The major problem is，light can get rid of the red color．When the team shone a bright light on the molecule，the broken bond was fixed，and the color disappeared．If bright fight keeps the red color from appearing，the material’s warning system will be useless．Scientists still have a lot of work to do before the color-changing molecule can be used outside the lab．

1. The passage mainly about

A. a way of preventing building from breaking down

B. a series of earthquakes in Haiti and Chile

C. a way of warning before buildings collapse

D. a newly-discovered structure of a molecule

2.According to the passage，we can conclude that

A．there are problems to solve before putting the new material to use

B．scientists have found the life circle of buildings from “birth” to “death”

C．bright fight makes the red color visible to human eyes[来源:Z&xx&k.Com]

D．the new material is unlikely to be used in building bridges

3.The color-changing molecule can

A．make building materials much stronger[来源:Zxxk.Com]

B．help building materials get stretched if necessary

C．prevent the earthquake from killing people

D．remind people to leave buildings before they fall

4.The warning system is based on the fact that

A．red color won’t show up when it meets bright fight

B．a material with a certain type of molecule Can turn red when stretched etched

C．a building has its own life circle of “birth” to “death”

D．the broken bond will fix itself when a molecule meets bright fight

 

  Things similar continuously happened in Haiti and Chile．Thousands of people were

buried in the earthquake and lost their fives．What if we could have warned them? People are always trying hard to find a way of preventing building collapsing(坍塌)．Better materials and technology help，but are not a solution．Just like humans，a building has its own life circle from  “birth” to “death”．If we know when a building is going to collapse，we can repair it in advance or get out before it falls．

    Now, scientists at the University of Illinois have developed a material that turns red before it breaks．The invention could be used in things like climbing ropes，or bridge supports．The secret behind the color-changing material is a type of molecule(分子)．A molecule is a group of atoms held together by chemical bonds(化学键)．Imagine you and your friends standing in a circle，holding hands．Each person stands for one atom，your hands represent the bonds，and the entire circle represents a molecule．If one person lets go of his or her hands，the molecule changes color．The research team put the molecule into a soft material．When the researchers stretched(拉长) the material：it turned bright red a few seconds before it broke into two pieces．

When they repeatedly stretched and relaxed the material，without breaking it，it only turned a little red．

The major problem is，light can get rid of the red color．When the team shone a bright light on the molecule，the broken bond was fixed，and the color disappeared．If bright fight keeps the red color from appearing，the material’s warning system will be useless．Scientists still have a lot of work to do before the color-changing molecule can be used outside the lab．

The passage mainly about

A. a way of preventing building from breaking down

B. a series of earthquakes in Haiti and Chile

C. a way of warning before buildings collapse

D. a newly-discovered structure of a molecule

According to the passage，we can conclude that

A．there are problems to solve before putting the new material to use

B．scientists have found the life circle of buildings from “birth” to “death”

C．bright fight makes the red color visible to human eyes

D．the new material is unlikely to be used in building bridges

The color-changing molecule can

A．make building materials much stronger

B．help building materials get stretched if necessary

C．prevent the earthquake from killing people

D．remind people to leave buildings before they fall

The warning system is based on the fact that

A．red color won’t show up when it meets bright fight

B．a material with a certain type of molecule Can turn red when stretched etched

C．a building has its own life circle of “birth” to “death”

D．the broken bond will fix itself when a molecule meets bright fight

Can you remember a morning when you’ve woken up to the ring of your alarm clock and wished you could stay in bed? You haven’t slept well, your hair is a mess. Worse, you can’t stop yawning. Yawning is universal to humans and many animals. Cats, dogs and fish yawn just like humans do! Yawning is an involuntary(无意识的,不自觉的) action during which you open your mouth and breathe deeply. The average duration of a yawn is about 6 seconds.

The purpose and cause of yawning are still a mystery. Scientists are not sure what causes a yawn. People yawn when they are tired or bored, but they also yawn when they aren’t. There are many ideas explaining why we yawn.

One idea is that yawning is a way for the body to become more alert by taking in more oxygen. A yawn increases the heart rate, forces carbon dioxide out of the lungs and blood stream, and brings oxygen to the brain. But one study showed that volunteers given a lot of oxygen did not yawn any less than before, while those given a lot of carbon dioxide did not yawn more.

Another idea is that early humans used yawning as a form of communication. If one decided it was time to sleep, they would tell the others by yawning and they would do it in return to show they agreed.

A third explanation comes from psychology professor Gordon Gallup of University at Albany in New York. He said that as people yawn, they cool off their brains. “Brains are like computers.” he said. “They only operate efficiently and effectively when they’re cool. Many things connected to yawning, like being tired, make the brain hot, and yawning can reduce the heat.”

Scientists have sent people into space, and created terrible nuclear weapons, but there are lots of seemingly simple things, such as why we yawn, or hiccup（打嗝）, that they can’t figure out. Next time you are in class in the morning, let out a big yawn and watch to see how many of your classmates yawn in response!

1.What’s the purpose of the description of how bad you may feel when you’re woken up in the morning?

A．To explain why humans yawn.

B．To explain how humans start yawning.

C．To lead into the topic of yawning.

D．To complain about being woken up by the clock.

2.Which is not among the possible reasons for yawning mentioned in the passage?

A．A way to show that you feel hot.

B．A way to get rid of carbon dioxide.

C．A way to cool off your brain.

D．A way to communicate.

3.In which situation are you likely to yawn?

A．When you feel frustrated.

B．The weather is hot.

C．Someone else yawns near you.

D．When you breathe in a lot of carbon dioxide.

4.What can we learn from the passage?

A．The real reason why humans and most animals yawn.

B．Hiccups are an involuntary human action similar to yawns.

C．The more an action can be studied, the easier it is to research.

D．Finding out why humans yawn should be easier than sending people into space.

 

C

  Things similar continuously happened in Haiti and Chile．Thousands of people were

buried in the earthquake and lost their fives．What if we could have warned them? People are always trying hard to find a way of preventing building collapsing(坍塌)．Better materials and technology help，but are not a solution．Just like humans，a building has its own life circle from  “birth” to “death”．If we know when a building is going to collapse，we can repair it in advance or get out before it falls．

    Now, scientists at the University of Illinois ha、，e developed a material that turns red before it breaks．The invention could be used in things like climbing ropes，or bridge supports．The secret behind the color-changing material is a type of molecule(分子)．A molecule is a group of atoms held together by chemical bonds(化学键)．Imagine you and your friends standing in a circle，holding hands．Each person stands for one atom，your hands represent the bonds，and the entire circle represents a molecule．If one person lets go of his or her hands，the molecule changes color．The research team put the molecule into a soft material．When the researchers stretched(拉长) the material：it turned bright red a few seconds before it broke into two pieces．

When they repeatedly stretched and relaxed the material，without breaking it，it only turned a little red．

The major problem is，light can get rid of the red color．When the team shone a bright light on the molecule，the broken bond was fixed，and the color disappeared．If bright fight keeps the red color from appearing，the material’s warning system will be useless．Scientists still have a lot of work to do before the color-changing molecule can be used outside the lab．

49.The passage is mainly about______________

A．a way of preventing building from breaking down

B．a series'-of earthquakes in Haiti and Chile

C．a way of warning before buildings collapse

D．a newly—discovered structure of a molecule

50.According to the passage，we call conclude that____________

A．there are problems to solve before putting the new material to use

B．scientists have found the life circle of buildings from “birth” to “death”

C．bright fight makes the red color visible to human eyes

D．the new material is unlikely to be used in building bridges

51.The color-changing molecule can___________

A．make building materials much stronger

B．help building materials get stretched if necessary

C．prevent the earthquake from killing people

D．remind people to leave buildings before they fall

52．The warning system is based on the fact that____________

A．red color won’t show up when it meets bright fight

B．a material with a certain type of molecule Can turn red when setched

C．a building has its own life circle of “birth”to“death”

D．the broken bond will fix itself when a molecule meets bright fight