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Have you ever wondered how a turtle (乌龟) got its shell? You’re not the only one. Paleontologists (古生物学家) have long been confused by the question. But a recently found turtle fossil (化石), the oldest on record, may hold the answer. Researchers report in Nature that the fossil show shells evolved as an extension of turtles’ backbones and ribs （肋骨）.
“The discovery opens a new chapter in the study of the origins and early history of these fascinating reptiles (爬行动物),” says paleontologist Robert Reisz of the University of Toronto.
Scientists have been in the dark until now because all turtle fossils previously discovered had complete shells. (The previously oldest known turtle was discovered in Germany. It dated to about 210 million years ago). But this 220 million-year-old fossil is an ancestor of the modern turtle at a stage when its shell was still evolving.
The 40cm-long fossil was discovered in Guizhou province. An international team of paleontologists led by Li Chun of Sciences in Beijing analyzed it. They reported that the bones belonged to a Triassic (三世纪的) turtle, which they named Odontochelys semitestacea, meaning “ toothed turtle with a half shell.”
The fossil has a shelled belly （腹部）and a little extra bone on its spine (脊柱). That supports the theory that turtles’ shells formed over time as their backbones and ribs grew. Before the discovery, some paleontologists thought shells were formed as hard, bony plates in turtles’ skin such as those in the skin of modern-day crocodile (鳄鱼) grow together.
The authors say that this turtle species probably lived in water and that their stomach shell kept them safe from predators (捕食者) below while they were swimming.
1. The passage is mainly about________ .
A. a brief introduction to the structure of turtle shells
B. a new insight about how turtle shells formed gradually
C. a brief introduction to the living habits of turtles
D. the study of the origins and early history of turtles
2. The newly found turtle fossil________ .
A. was found by Li Chun, one Chinese paleontologist.
B. Was found in southwestern China
C. Shows that turtle shells evolved from turtles’
backbones and bellies.
D. makes the scientists know how turtle shells evolved with the help of the fossil.
3. What can we conclude from the passage?
A. The newly found fossil plays a key role in studying the origins of reptiles.
B. Paleontologists think turtle shells developed from turtles’ hard skin.
C. Some species of turtles don’t have stomach shells because they live on land
D. Paleontologists have long been puzzled about what makes up turtle shells
4. “Nature”, mentioned in Paragraph 1, is most probably the name of________ .
A. a science fiction B. a magazine on science
C. a photo website D. a science organization
B
Today there are 4 billion people around the word with cellphones (手机). As cellphone numbers have grown,so have fears about their safety.
Scientists have not found a definite (确定的) link （联系） between cellphones and cancer,but studies do suggest an increased risk (风险) for those who have used the phones for 10 years or more.
“There’s enough concern that the governments of six countries including France, Germany and Israel have limited (限制) the usage of cellphones, particularly for children,”says Jane Houlihan. She is vice president of the US’ Environmental Working Group.
The group did a study recently. They found that some cellphones give out several times more radiation than others. They have published a list with the radiation levels of 1,000cellphones. (forthelist,visithttp://www.ewg. org/cellphoneradiation) Houlihan says her group thinks people should choose a phone with lower radiation.
The following suggestions may also help you to cut your risk.
1. Use a headset (耳机) or speaker
Headsets give out much less radiation than phones. Some wireless headsets do give out low-level radiation,so take yours off your ear when you’re not on a call. Using your phone with a speaker will also reduce your risk.
2. Listen more, talk less
Your phone gives out radiation when you talk or text, but not when you’re getting messages. Listening more and talking less reduces your risk.
3. Hold the phone away from your body
Hold the phone away from your body when you’re talking(with headset or speaker ), not against your ear ,in a pocket or on your belt.
4. Choose texting over talking
phones use less power(less radiation)to send text than voice. And unlike when you speak with the phone at your ear texting keeps radiation away from your head.
5. Poor signal? Stay off the phone
Fewer signal bars(格)on your phone means that the phone is giving out more radiation. Make and take calls when your phone has a strong signal.
1. Scientists are concerned about the increasing usage of cell phones because________
A. there is an obvious link between the use of cellphone and cancer
B. cellphones give out radiation strong enough to cause cancer
C. studies suggest an increased risk of cancer for cellphone users of 10 years or more
D. people spend more time on their cellphones than before.
1. What does the underlined word “radiation” in Paragraph 4 mean?
A. a piece of electronic equipment which you use to listen to programmes.
B. A form of energy which is very harmful to living things if present in large amounts.
C. the signal
D. the amount of the battery’s power
2. In which of the following situations would it be better Not to use a cell phone?
A. When your battery is running out.
B. When you don’t have a headset.
C. When the signal is poor.
D. When you can send a text message instead.
3. Which of the following statements is TRUE?
A. Cellphone radiation does less harm to children.
B. The 1,000 cellphones on the US’s Environmental Working Group List are safe.
C. You should keep your cellphone in your pocket or on your belt while talking with a headset.
D. Send a text message when you do not need to make a call.
“The discovery opens a new chapter in the study of the origins and early history of these fascinating reptiles (爬行动物),” says paleontologist Robert Reisz of the University of Toronto.
Scientists have been in the dark until now because all turtle fossils previously discovered had complete shells. (The previously oldest known turtle was discovered in Germany. It dated to about 210 million years ago). But this 220 million-year-old fossil is an ancestor of the modern turtle at a stage when its shell was still evolving.
The 40cm-long fossil was discovered in Guizhou province. An international team of paleontologists led by Li Chun of Sciences in Beijing analyzed it. They reported that the bones belonged to a Triassic (三世纪的) turtle, which they named Odontochelys semitestacea, meaning “ toothed turtle with a half shell.”
The fossil has a shelled belly （腹部）and a little extra bone on its spine (脊柱). That supports the theory that turtles’ shells formed over time as their backbones and ribs grew. Before the discovery, some paleontologists thought shells were formed as hard, bony plates in turtles’ skin such as those in the skin of modern-day crocodile (鳄鱼) grow together.
The authors say that this turtle species probably lived in water and that their stomach shell kept them safe from predators (捕食者) below while they were swimming.
1. The passage is mainly about________ .
A. a brief introduction to the structure of turtle shells
B. a new insight about how turtle shells formed gradually
C. a brief introduction to the living habits of turtles
D. the study of the origins and early history of turtles
2. The newly found turtle fossil________ .
A. was found by Li Chun, one Chinese paleontologist.
B. Was found in southwestern China
C. Shows that turtle shells evolved from turtles’
backbones and bellies.
D. makes the scientists know how turtle shells evolved with the help of the fossil.
3. What can we conclude from the passage?
A. The newly found fossil plays a key role in studying the origins of reptiles.
B. Paleontologists think turtle shells developed from turtles’ hard skin.
C. Some species of turtles don’t have stomach shells because they live on land
D. Paleontologists have long been puzzled about what makes up turtle shells
4. “Nature”, mentioned in Paragraph 1, is most probably the name of________ .
A. a science fiction B. a magazine on science
C. a photo website D. a science organization
B
Today there are 4 billion people around the word with cellphones (手机). As cellphone numbers have grown,so have fears about their safety.
Scientists have not found a definite (确定的) link （联系） between cellphones and cancer,but studies do suggest an increased risk (风险) for those who have used the phones for 10 years or more.
“There’s enough concern that the governments of six countries including France, Germany and Israel have limited (限制) the usage of cellphones, particularly for children,”says Jane Houlihan. She is vice president of the US’ Environmental Working Group.
The group did a study recently. They found that some cellphones give out several times more radiation than others. They have published a list with the radiation levels of 1,000cellphones. (forthelist,visithttp://www.ewg. org/cellphoneradiation) Houlihan says her group thinks people should choose a phone with lower radiation.
The following suggestions may also help you to cut your risk.
1. Use a headset (耳机) or speaker
Headsets give out much less radiation than phones. Some wireless headsets do give out low-level radiation,so take yours off your ear when you’re not on a call. Using your phone with a speaker will also reduce your risk.
2. Listen more, talk less
Your phone gives out radiation when you talk or text, but not when you’re getting messages. Listening more and talking less reduces your risk.
3. Hold the phone away from your body
Hold the phone away from your body when you’re talking(with headset or speaker ), not against your ear ,in a pocket or on your belt.
4. Choose texting over talking
phones use less power(less radiation)to send text than voice. And unlike when you speak with the phone at your ear texting keeps radiation away from your head.
5. Poor signal? Stay off the phone
Fewer signal bars(格)on your phone means that the phone is giving out more radiation. Make and take calls when your phone has a strong signal.
1. Scientists are concerned about the increasing usage of cell phones because________
A. there is an obvious link between the use of cellphone and cancer
B. cellphones give out radiation strong enough to cause cancer
C. studies suggest an increased risk of cancer for cellphone users of 10 years or more
D. people spend more time on their cellphones than before.
1. What does the underlined word “radiation” in Paragraph 4 mean?
A. a piece of electronic equipment which you use to listen to programmes.
B. A form of energy which is very harmful to living things if present in large amounts.
C. the signal
D. the amount of the battery’s power
2. In which of the following situations would it be better Not to use a cell phone?
A. When your battery is running out.
B. When you don’t have a headset.
C. When the signal is poor.
D. When you can send a text message instead.
3. Which of the following statements is TRUE?
A. Cellphone radiation does less harm to children.
B. The 1,000 cellphones on the US’s Environmental Working Group List are safe.
C. You should keep your cellphone in your pocket or on your belt while talking with a headset.
D. Send a text message when you do not need to make a call.