For those who can stomach it, working out before breakfast may be more beneficial for health than eating first, according to a study of meal timing and physical activity.
Athletes and scientists have long known that meal timing affects performance. However, far less has been known about how meal timing and exercise might affect general health.
To find out, British scientists conducted a study. They first found 10 overweight and inactive but otherwise healthy young men, whose lifestyles are, for better and worse, representative of those of most of us. They tested the men's fitness and resting metabolic (新陈代谢的) rates and took samples (样品) of their blood and fat tissue.
Then, on two separate morning visits to the scientists' lab, each man walked for an hour at an average speed that, in theory should allow his body to rely mainly on fat for fuel. Before one of these workouts, the men skipped breakfast, meaning that they exercised on a completely empty stomach after a long overnight fast (禁食). On the other occasion, they ate a rich morning meal about two hours before they started walking.
Just before and an hour after each workout, the scientists took additional samples of the men's blood and fat tissue.
Then they compared the samples. There were considerable differences. Most obviously, the men displayed lower blood sugar levels at the start of their workouts when they had skipped breakfast than when they had eaten. As a result, they burned more fat during walks on an empty stomach than when they had eaten first. On the other hand, they burned slightly more calories (卡路里), on average, during the workout after breakfast than after fasting.
But it was the effects deep within the fat cells that may have been the most significant, the researchers found. Multiple genes behaved differently, depending on whether someone had eaten or not before walking. Many of these genes produce proteins (蛋白质) that can improve blood sugar regulation and insulin (胰岛素) levels throughout the body and so are associated with improved metabolic health. These genes were much more active when the men had fasted before exercise than when they had breakfasted.
The implication of these results is that to gain the greatest health benefits from exercise, it may be wise to skip eating first.
Cloning is defined as using the cells of one living subject, plant or animal, to create another duplicate (复制的) subject. A cloned subject will be the same as its parent. This technology could be useful for laboratory studies and for creating satisfying animals.
One of the biggest disadvantages of cloning is that the technology is still so uncertain. Dolly the sheep, the first mammalian clone, was born in 1996. While she was initially successful, she died young of a disease not normally seen in sheep of her age.
Losing gene diversity is another disadvantage of cloning. Gene diversity is what keeps an entire species from being wiped out by a singular virus. If gene diversity is lost due to excessive cloning, there are no mutations to allow some of the cloned group to survive a newly introduced disease.
Another of the disadvantages of cloning is that there are a lot of moral considerations that would cause most people to protest. Another concern is the treatment of clones. Clones would have the same needs as nonclones of their species. Humane treatment guidelines would still apply.
For example, imagine what a corrupt (腐败的) officer could do with cloning. There will always be someone looking to use cloning for their own personal use, and many feel that the best way to prevent this is not to pursue cloning at all.
The disadvantages of cloning are seen by many to far outweigh any benefits that might be seen. Because of the risk involved in cloning, it is a technology that many experts say may be better left alone, at least until it is better understood.
A. This is due to the lack of gene diversity.
B. One of these ethical concerns is that cloning is unnatural.
C. There is always a risk of cloning technology being abused.
D. There are many advantages of cloning, for example, curing certain diseases.
E. However, there are several disadvantages of cloning that should be considered.
F. It helps to explain why some people naturally are taller, shorter, or more athletic than others.
G. It is still unsure whether genetic mutations (突变) might occur when an animal is cloned.
Going to Mount Huangshan reminds me of the popular Beatles' song" The Long and Winding Road". is so breathtaking about the experience is the outofthisworld scenes. The rolling sea of clouds you see once you are at the top will remind you how tiny we (human) are.
The hot spring at the foot of the mountain is something you must try after the climb. It will (undoubted) help you get refreshed! The amazing thing about the spring is that the colder the temperature gets, the (hot) the spring! Strange, isn't it? But that's how nature is — always leaving us (astonish).
What comes next is the endless series of steps. You can't help wondering how hard it (be) for the people then to put all those rocks into place. Though it is the only unnatural thing on your way up the mountain, still it highlights the whole adventure offers a place where you can sit down to rest your (ache) legs.
As the song goes, this long and winding road "will never disappear", and it will always stick in the visitor's memory. It sure does in (I). While you're in China, Mount Huangshan is must to visit!
阅读下面材料, 根据其内容和所给段落开头语续写两段, 使之构成一篇完整的短文。
Jenny was a brighteyed, pretty fiveyearold girl. One day when she and her mother were checking out at the grocery store, Jenny saw a plastic pearl necklace which was priced at $2. 50. How she wanted that necklace, and when she asked her mother if she would buy it for her, her mother said," Well, it is a pretty necklace, but it costs an awful lot of money. I'll tell you what. I'll buy you the necklace, and when we get home we can make up a list of chores that you can do to pay for the necklace. And don't forget that for your birthday grandma just might give you a whole dollar bill, too. Okay?" Jenny agreed happily, and her mother bought the pearl necklace for her.
Jenny worked on her chores very hard every day, and sure enough, her grandma gave her a brand new dollar bill for her birthday. Soon Jenny had paid off the pearls. How Jenny loved those pearls! She wore them everywhere to kindergarten, bed and even when she went out with her mother to run errands.
The only time she didn't wear them was in the shower because her mother had told her that they would turn her neck green!
Jenny had a very loving Daddy. When Jenny went to bed, he would get up from his favourite chair every night and read Jenny her favourite story.
One night when he finished the story, he asked Jenny," Hey, sweetie, do you love me?"
"Oh yes, Daddy, you know I love you," the little girl said with a warm smile.
"Well, then, give me your pearls."
"Oh! Daddy, not my pearls!" Jenny refused." But you can have Rosy, my favourite doll. Remember her? You gave her to me last year for my birthday. And you can have her tea party outfit, too. Okay?"
"Oh no, darling, that's okay." Her father brushed her cheek with a kiss." Good night, little one. "
注意：1）续写词数应为150左右；
2）请按如下格式作答。
A week later, Jenny's father once again asked Jenny the same question after her story,
……
Another week later, when her father came in to read her a story as usual,
