题目内容

一Is Johnson on duty today?

　 一It ________be him．It’s my turn.

　 A．may not　　　 B．won’t　　　　 　 C．mustn’t　　　 　 D．can’t

 

D

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—Excuse me, where is Johnson?

—He cannot go home, as his book is lying __________on his desk.

A．openly

B．opening

C．opened

D．open

 

A breathtaking trick potentially left over from our ancestors might be found in us — the ability to sense oxygen through our skin.

Amphibians, animals such as frogs that can live both on land and in water, have long been known to be capable of breathing through their skin. In fact, the first known lungless frog that breathes only through its skin was discovered recently in the rivers of Borneo.

Now the same oxygen sensors found in frog skins and in the lungs of mammals (哺乳动物) have unexpectedly been discovered in the skin of mice.

“No one had ever looked,” explained Randall Johnson, a biologist researcher.

Mice and frogs are quite distant relatives, so the fact they have these molecules (分子) in common in their skin suggests they might well be found in the skin of other mammals, such as humans.

“We have no reason to think that they are not in the skin of people too,” Johnson said.   These molecules not only detect oxygen, but help increase levels of vital red blood cells, which carry oxygen around the body. Normal mice breathing in air that is 10 percent oxygen—a dangerously low level similar to conditions at the top of Mount Everest, and about half that of air at sea level. However, mice that had the oxygen sensor HIF-1a genetically removed from their skin failed to produce this hormone (荷尔蒙) even after hours of such low oxygen.

These findings, if they hold true in humans, suggest one could raise the level of oxygen circulating inside the body. This could help treat lung diseases and disorders such as anemia (贫血症) without injecting drugs, which make up a multibillion-dollar market, Johnson said.

Athletes also often try to get more oxygen delivered to their muscles in order to improve their performance. They often do this by training at high altitudes or in low-oxygen tents. The new study suggests they might want to expose their skin as well as breathing in low-oxygen air to improve their performance. “It’s hard to say what exactly might be done, however—there’s a lot we don’t know yet,” Johnson explained.

The scientists detailed their findings in the April 18 issue of the journal Cell.

49. Which of the following statements is TRUE according to the passage?

A. Johnson believes that Oxygen sensors also exist in human skin.

B. People have to surf the Internet to read detailed findings.

C. It has been proved that these findings help treat lung diseases.

D. It has long been expected oxygen sensors exist in mice’s skin. 

50. One of the functions of the molecules mentioned above is _______.

A. carrying oxygen around the body                   B. improving athletes’ performance

C. detecting oxygen                                          D. increasing level of oxygen

51. What is Johnson’s attitude to the application of the findings to the athletes’ training?

A. Negative                  B. Doubting                  C. Positive             D. Hesitating

52. The best title of the passage may be _______.

A. Great Findings Benefits Athletes A Lot

B. Frogs And Mice Are Distant Relatives

C. First Known Animal Breathes Through Skin

D. Humans Might Sense Oxygen Through Skin

 

根据对话内容，从对话后的选项中选出能填入空白处的最佳选项，并在答题卡上将该项涂黑。选项中有两项为多余选项。

一Hello.Gerry speaking．

一Hdlo．Gerry．It’s me John here． 1

一Well．I’m terribly sorry．bat I’m not feeling very well．

一Is that all? 2

一No．I’m sony．I was sick all night．I think it must be the fish I ate last night．

一Well．I think you should have at least phoned Kate and told her you weren’t coming to the meeting．

----3  I’m sorry about that．Anyway，I think I’ll be able to get in to work tomorrow．

一4

一I won’t．Thanks for calling．

一5

A．Why didn’t you phone?

B．OK．Take care and don’t eat any more fish．

C．Why aren’t you here at the meeting?

D．That’s all right．

E．We thought you might have had an accident or forgotten the day or something.

F．I’ll be glad tosee you again.

G．Yes．I suppose I should have done so.

 

 

一Is Johnson on duty today?

一It ________be him．It’s my turn.

A．may not          B．won’t               C．mustn’t         D．can’t

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