在VHDL中，可以用语句（）表示检测clock下降沿。

A:clock’event B:clock’eventandclock=’1’ C:clock=’0’ D:clock’eventandclock=’0’

Memory Class Stan Field knows what age can do to a person’’s memory, and he’’s not taking any chances with his. He chooses his food carefully and gets plenty of exercise. He also avoids stress, coca cola and cigarette smoke. What’’s more, at breakfast each morning, the 69-year-old chemical engineer swallows a plateful of pills in the hope of boosting his brain power. Michelle Amove is less than half Field’’s age, but no less concerned about her memory. While working round the clock to finish a degree in film studies, the 33-year-old New Yorker had the alarming sensation that she had stopped retaining anything. "I couldn’’t even remember names," she says. "I thought, Oh, no, I’’m over 30. It’’s all downhill from here. " Besides loading up on supplements, Amove signed up for a memory enhancing course at New York’’s Mount Siani Medical Center. And when she got there, she found herself surrounded by people who were just as worried as she was. For millions of Americans, and especially for baby boomers (生育高峰出生的人) , the demands of the Information Age conflict with a sense of declining physical power. "When boomers were in their 30s and 40s, they launched the fitness boom," says Cynthia Green, the psychologist who teaches Mount Sinai’’s memory class. "Now we have the mental-fitness boom Memory is the boomers’’ new life-crisis issue." And of course a major marketing opportunity. The demand for books and seminars has never been greater, says Jack Lannom, a longtime memory trainer whose weekly TV show, " Mind Unlimited," goes out to 33 million homes on the Christian Network. Anxious consumers are rushing to buy do-it-yourself programs and supplement makers are trying to sell everything but sawdust (木屑) as a brain booster. But before you get out your checkbook, a few questions are in order. Does everyday forgetfulness signal declining brain function? Is "megamemory" (超级记忆) a realistic goal for normal people? And if you could have a perfect memory, would you really want it? Until recently, no one could address those issues with much authority, but our knowledge of memory is exploding. New techniques are revealing how different parts of the brain interact to preserve meaningful experiences. Biologists are trying to understand the underlying (潜在的) chemical processes and neuroscientists (神经系统科学家) are discovering how age, stress and other factors can disrupt them. No one is close to finding the secret to perfect recall, but as you’’ll see, that may be just as well. What is the meaning of "working round the clock" ?

A:Working day and night. B:Making clocks. C:Working with a clock nearby. D:Repairing clocks.

? ?下面有3篇短文，每篇短文后有5道题。请根据短文内容，为每题确定1个最佳选项。
{{B}}第一篇{{/B}}

A:The importance of timing. B:The working principle of an ordinary clock. C:The features of the U.S. Atomic Clock. D:The manufacturer of the U.S. Atomic Clock.

What is the meaning of "working round the clock"?

A:Repairing clocks. B:Making clocks. C:Working with a clock nearby. D:Working day and night.

Memory Class Stan Field knows what age can do to a person’’s memory, and he’’s not taking any chances with his. He chooses his food carefully and gets plenty of exercise. He also avoids stress, coca cola and cigarette smoke. What’’s more, at breakfast each morning, the 69-year-old chemical engineer swallows a plateful of pills in the hope of boosting his brain power. Michelle Amove is less than half Field’’s age, but no less concerned about her memory. While working round the clock to finish a degree in film studies, the 33-year-old New Yorker had the alarming sensation that she had stopped retaining anything. "I couldn’’t even remember names," she says. "I thought, Oh, no, I’’m over 30. It’’s all downhill from here. " Besides loading up on supplements, Amove signed up for a memory enhancing course at New York’’s Mount Siani Medical Center. And when she got there, she found herself surrounded by people who were just as worried as she was. For millions of Americans, and especially for baby boomers (生育高峰出生的人) , the demands of the Information Age conflict with a sense of declining physical power. "When boomers were in their 30s and 40s, they launched the fitness boom," says Cynthia Green, the psychologist who teaches Mount Sinai’’s memory class. "Now we have the mental-fitness boom Memory is the boomers’’ new life-crisis issue." And of course a major marketing opportunity. The demand for books and seminars has never been greater, says Jack Lannom, a longtime memory trainer whose weekly TV show, " Mind Unlimited," goes out to 33 million homes on the Christian Network. Anxious consumers are rushing to buy do-it-yourself programs and supplement makers are trying to sell everything but sawdust (木屑) as a brain booster. But before you get out your checkbook, a few questions are in order. Does everyday forgetfulness signal declining brain function? Is "megamemory" (超级记忆) a realistic goal for normal people? And if you could have a perfect memory, would you really want it? Until recently, no one could address those issues with much authority, but our knowledge of memory is exploding. New techniques are revealing how different parts of the brain interact to preserve meaningful experiences. Biologists are trying to understand the underlying (潜在的) chemical processes and neuroscientists (神经系统科学家) are discovering how age, stress and other factors can disrupt them. No one is close to finding the secret to perfect recall, but as you’’ll see, that may be just as well. What is the meaning of "working round the clock" ?

A:Working day and night. B:Making clocks. C:Working with a clock nearby. D:Repairing clocks.

Memory Class Stan Field knows what age can do to a person’’s memory, and he’’s not taking any chances with his. He chooses his food carefully and gets plenty of exercise. He also avoids stress, coca cola and cigarette smoke. What’’s more, at breakfast each morning, the 69-year-old chemical engineer swallows a plateful of pills in the hope of boosting his brain power. Michelle Amove is less than half Field’’s age, but no less concerned about her memory. While working round the clock to finish a degree in film studies, the 33-year-old New Yorker had the alarming sensation that she had stopped retaining anything. "I couldn’’t even remember names," she says. "I thought, Oh, no, I’’m over 30. It’’s all downhill from here. " Besides loading up on supplements, Amove signed up for a memory enhancing course at New York’’s Mount Siani Medical Center. And when she got there, she found herself surrounded by people who were just as worried as she was. For millions of Americans, and especially for baby boomers (生育高峰出生的人) , the demands of the Information Age conflict with a sense of declining physical power. "When boomers were in their 30s and 40s, they launched the fitness boom," says Cynthia Green, the psychologist who teaches Mount Sinai’’s memory class. "Now we have the mental-fitness boom Memory is the boomers’’ new life-crisis issue." And of course a major marketing opportunity. The demand for books and seminars has never been greater, says Jack Lannom, a longtime memory trainer whose weekly TV show, " Mind Unlimited," goes out to 33 million homes on the Christian Network. Anxious consumers are rushing to buy do-it-yourself programs and supplement makers are trying to sell everything but sawdust (木屑) as a brain booster. But before you get out your checkbook, a few questions are in order. Does everyday forgetfulness signal declining brain function? Is "megamemory" (超级记忆) a realistic goal for normal people? And if you could have a perfect memory, would you really want it? Until recently, no one could address those issues with much authority, but our knowledge of memory is exploding. New techniques are revealing how different parts of the brain interact to preserve meaningful experiences. Biologists are trying to understand the underlying (潜在的) chemical processes and neuroscientists (神经系统科学家) are discovering how age, stress and other factors can disrupt them. No one is close to finding the secret to perfect recall, but as you’’ll see, that may be just as well. What is the meaning of "working round the clock" ?

A:Working day and night. B:Making clocks. C:Working with a clock nearby. D:Repairing clocks.

Memory Class Stan Field knows what age can do to a person’’s memory, and he’’s not taking any chances with his. He chooses his food carefully and gets plenty of exercise. He also avoids stress, coca cola and cigarette smoke. What’’s more, at breakfast each morning, the 69-year-old chemical engineer swallows a plateful of pills in the hope of boosting his brain power. Michelle Amove is less than half Field’’s age, but no less concerned about her memory. While working round the clock to finish a degree in film studies, the 33-year-old New Yorker had the alarming sensation that she had stopped retaining anything. "I couldn’’t even remember names," she says. "I thought, Oh, no, I’’m over 30. It’’s all downhill from here. " Besides loading up on supplements, Amove signed up for a memory enhancing course at New York’’s Mount Siani Medical Center. And when she got there, she found herself surrounded by people who were just as worried as she was. For millions of Americans, and especially for baby boomers (生育高峰出生的人) , the demands of the Information Age conflict with a sense of declining physical power. "When boomers were in their 30s and 40s, they launched the fitness boom," says Cynthia Green, the psychologist who teaches Mount Sinai’’s memory class. "Now we have the mental-fitness boom Memory is the boomers’’ new life-crisis issue." And of course a major marketing opportunity. The demand for books and seminars has never been greater, says Jack Lannom, a longtime memory trainer whose weekly TV show, " Mind Unlimited," goes out to 33 million homes on the Christian Network. Anxious consumers are rushing to buy do-it-yourself programs and supplement makers are trying to sell everything but sawdust (木屑) as a brain booster. But before you get out your checkbook, a few questions are in order. Does everyday forgetfulness signal declining brain function? Is "megamemory" (超级记忆) a realistic goal for normal people? And if you could have a perfect memory, would you really want it? Until recently, no one could address those issues with much authority, but our knowledge of memory is exploding. New techniques are revealing how different parts of the brain interact to preserve meaningful experiences. Biologists are trying to understand the underlying (潜在的) chemical processes and neuroscientists (神经系统科学家) are discovering how age, stress and other factors can disrupt them. No one is close to finding the secret to perfect recall, but as you’’ll see, that may be just as well. What is the meaning of "working round the clock" ?

A:Working day and night. B:Making clocks. C:Working with a clock nearby. D:Repairing clocks.