在气体的流动过程中流体流动类型为湍流时Re（）。

A:Re＜2320 B:＞10000 C:2320＜Re＜10000 D:Re与液体流动无关

当（）时，可用公式λ=64/Re来计算沿程阻力系数。

A:紊流 B:Re〈2000 C:Re〉2000

雷诺数Re可用来判别流体的流动状态，当（）时是层流状态。

A:Re小于2300 B:Re大于2300 C:Re大于1000 D:Re小于1000

雷诺系数Re可用来判别流体的流动状态，当（）是层流状态。

A:Re＜2000 B:Re＞2000 C:Re＞1000 D:Re＜1000

流体在直管内流动时，当雷诺数Re（）时，流体的流动属于湍流。

A:Re≥4000 B:Re≤2000 C:Re≥3000 D:2000≤Re≤4000

有压圆管恒定流，若断面1的直径是其下游断面2的直径的二倍，则断面1的雷诺数Re1与断面2的雷诺数Re2的关系是：（）

A:Re1=Re2 B:Re1=0.5Re2 C:Re1=1.5Re2 D:Re1=2Re2

Digital photography is still new enough that most of us have yet to form an opinion about it, (1) develop a point of view. But this bash’ t stopped many film and computer fans from agreeing (2) the early conventional wisdom about digital cameras—they’ re nea (3) for you But they’re not suitable for everyday picture taking.
The fans are wrong: Moro than anything else, digital cameras are radically (4) what photography means and what it can be. The venerable medium of photography (5) we know it is beginning to seem out of (6) with the way we live. In our computer and camcorder (7) saving pictures as digital (8) and watching them on TV is no less practical—and in many ways more (9) than fumbling with rolls of film that must be sent off to be (10) .
Paper is also terribly (11) . Pictures that are incorrectly framed, (12) ,or lighted are nonetheless committed to film and ultimately processed into prints.
The digital medium changes the (13) . Still images that are (14) digitally can immediately be shown on a computer (15) , a TV screen, or a small liquid -crystal display (LCD) built fight into the camera. And since the points of light that (16) an image are saved as a series of digital bits in electronic memory, (17) being permanently etched onto film, they can be erased, retouched, and transmitted (18) .
What’s it like to (19) with one of these digital cameras It’s a little like a first date--exciting, confusing and fraught with (20) .

Read the following text. Choose the best word(s) for each numbered blank and mark A, B, C, and D on ANSWER SHEET 1.16（）

A:re-explaining B:rearranging C:re-exposing D:redefining

Digital photography is still new enough that most of us have yet to form an opinion about it, (1) develop a point of view. But this hasn’t stopped many film and computer fans from agreeing (2) the early conventional wisdom about digital cameras—they’re neat (3) for your PC, but they’re not suitable for everyday picture-taking.
The fans are wrong: More than anything else, digital cameras are radically (4) what photography means and what it can be. The venerable medium of photography (5) we know it is beginning to seem out of (6) with the way we live. In our computer and camcorder (7) , saving pictures as digital (8) and watching them on TV is no less practical—and in many ways more (9) than fumbling with rolls of film that must be sent off to be (10) .
Paper is also terribly (11) Pictures that are incorrectly framed, (12) , or lighted are nonetheless committed to film and ultimately processed into prints.
The digital medium changes the (13) . Still images that are (14) digitally can immediately be shown on a computer (15) , a TV screen, or a small liquid-crystal display (LCD) built right into the camera. And since the points of light that (16) an image are saved as a series of digital bits in electronic memory, (17) being permanently etched onto film, they can be erased, retouched, and transmitted (18) .
What’s it like to (19) with one of these digital cameras It’s a little like a first date- exciting, confusing and fraught with (20) .

Read the following text. Choose the best word (s) for each numbered blank and mark A, B, C or D on ANSWER SHEET 1.4（）

A:re-explaining B:rearranging C:re-exposing D:redefining

Digital photography is still new enough that most of us have yet to form an opinion about it, (1) develop a point of view. But this bash’ t stopped many film and computer fans from agreeing (2) the early conventional wisdom about digital cameras—they’ re nea (3) for you But they’re not suitable for everyday picture taking.
The fans are wrong: Moro than anything else, digital cameras are radically (4) what photography means and what it can be. The venerable medium of photography (5) we know it is beginning to seem out of (6) with the way we live. In our computer and camcorder (7) saving pictures as digital (8) and watching them on TV is no less practical—and in many ways more (9) than fumbling with rolls of film that must be sent off to be (10) .
Paper is also terribly (11) . Pictures that are incorrectly framed, (12) ,or lighted are nonetheless committed to film and ultimately processed into prints.
The digital medium changes the (13) . Still images that are (14) digitally can immediately be shown on a computer (15) , a TV screen, or a small liquid -crystal display (LCD) built fight into the camera. And since the points of light that (16) an image are saved as a series of digital bits in electronic memory, (17) being permanently etched onto film, they can be erased, retouched, and transmitted (18) .
What’s it like to (19) with one of these digital cameras It’s a little like a first date--exciting, confusing and fraught with (20) .

Read the following text. Choose the best word(s) for each numbered blank and mark A, B, C, and D on ANSWER SHEET 1.11（）

A:re-explaining B:rearranging C:re-exposing D:redefining

第二篇 Cell phones: hang up or keep talking Millions of people are using cell phones today. In many places it is actually considered unusual not to use one. In many countries, cell phones are very popular with young people. They find that the phones are more than a means of communication—having a mobile phone shows that they are cool and connected. The explosions around the world in mobile phone use make some health professionals worried.Some doctors are concerned that in the futre many people may suffer health problems from the use of mobile phones. In England, there has been a serious debate about this issue. Mobile phone companies are worried about the negative publicity of such ideas. They say that there is no proof that mobile phones are bad for your health. On the other hand, why do some medical studies show changes in the brain cells of some people who use mobile phones? Signs of change in the tissues of the brain and head can be detected with modern scanning(扫描) equipment. In one case, a traveling salesman had to retire at a young age because of serious memory loss. He couldn’t remember even simple tasks. He would often forget the name of his own son. This man used to talk on his mobile phone for about six hours a day,every day of his working week, for a couple of years. His family doctor blamed his mobile phone use, but his employer’s doctor didn’t agree. What is it that makes mobile phones potentially harmful? The answer is radiation. High-tech machines can detect very small amounts of radiation from mobile phones. Mobile phone companies agree that there is some radiation, but they say the amount is too small to worry about. As the discussion about their safety continues, it appears that it’s best to use mobile phones less often. Use your regular phone if you want to talk for a long time. Use your mobile phone only when you really need it. Mobile phones can be very useful and convenient, especially in emergencies. In the future, mobile phones may have a warning label that says they are bad for your health. So for now, it’s wise not to use your mobile phone too often.People buy cell phones for the following reasons EXCEPT that

A:they’re popular. B:they’re cheap. C:they’re useful. D:they’re convenient