Introductory Chemistry was taught at Duke University for many years by professor Bonk. One year, two guys took the class and did pretty well on all the quizzes and mid terms. They each had a solid A. These two friends were so confident in going into the final that the weekend before finals week,despite the Chemistry final being on Monday,they decided to go to the University of Virginia to party with some friends.

    They had a great time there. However,with their hangovers(宿醉) and tiredness,they overslept all day Sunday and didn't make it back to Duke until early Monday morning. Rather than taking the final then,they found professor Bonk after the final and explained to him how they missed the final. They told him they went up to the University of Virginia for the weekend and had planned to come back in time to study,but they had a flat tire on the way back and didn't have a spare. So they were late getting back to campus.

    Bonk thought this over and agreed that they could take the final the following day. The two guys,happily and relieved,studied that night and went in the next day at the time that Bonk had told them. He placed them in separate rooms and handed each of them a test booklet. He told them to begin.

    They looked at the first problem which was something simple about solution(溶解).It was worth 5 points. "Cool," they thought,"this is going to be an easy final". They then turned the page. They were unprepared,however,for what they saw on it. The question contained only two words: (95 points) Which tire?

    Anyone can write a baby poem, and everyone enjoys reading them, young and old. Baby shower(婴儿洗礼) poems can have rhythm and rhyme, but they certainly don't have to. Poems can be either long or short, but short is probably best for your typical baby shower needs. You can add a little humor as well!

    The people who are most often touched by baby shower poems are those who have had children themselves. Sweet poems can remind them of the time when their little ones were still young. No one will appreciate them more than the family members themselves. If you are a creative writer or  have a special talent for putting words together in a special way, then you should try writing your own baby shower poems. This would make a great gift idea as well.

    If you decide to write your own baby poems, even common things can inspire you. Inspiration can be found anywhere. Look to your own memories from the past. What was special about your childhood? What special object have you treasured over the years? What words of wisdom(智慧) of advice could you pass on to the next generation? Look around the house and imagine a baby being there. What do you see, hear, or feel? Let those thoughts be the source of your best baby poems.

    When writing a baby poem, you do not have to write like Shakespeare, you just have to be sincere. Years later when the baby has grown，think of how special they will feel knowing the words were just for them.

    If you are not the creative type — don't worry! There are lots of places online where you can look for poems saying just the things you want to say. Poems have been written on all subjects throughout the ages, and baby poems and baby shower poems are no exception. A quick search online doesn't have to take any time at all.

    Even plant can run a fever, especially when they're under attack by insects or disease. But unlike human, plants can have their temperature taken from 3,000 feet away straight up. A decade ago, adopting the infrared（红外线） scanning technology developed for military purposes and other satellites, physicist Stephen Paley came up with a quick way to take the temperature of crops to determine which ones are under stress. The goal was to let farmers precisely（精确的） target pesticide（杀虫剂） spraying rather than rain poison on a whole field, which always includes plants that don't have pest problems.

    Even better, Paley's Remote Scanning Services Company could detect crop problems before they became visible to the eye. Fixed on a plane flown at 3,000 feet at night, an infrared scanner measured the heat sent out by crops. The data were transformed into a color﹣coded map showing where plants were running "fevers". Farmers could then spot﹣spray, using 50 to 70 percent less pesticide that they otherwise would.

    The bad news is that Paley's company closed down in 1984, after only three years. Farmers resisted the new technology and long﹣term supporters were hard to find. But with the renewed concern about pesticides on produce and refinements（改进） in infrared scanning, Paley hopes to get back into operation. Agriculture experts have no doubt that the technology works. "This technique can be used on 75 percent of agricultural land in the United States," says George Oerther of Texas A&M, who recently retired from the Department of Agriculture, thinks remote infrared crop scanning could be adopted by the end of the decade. But only if Paley finds the financial support which he failed to obtain 10years ago.

    People traveling long distances frequently have to decide whether they would prefer to go by land, sea, or air. Hardly can anyone positively enjoy sitting in a train for more than a few hours. Train carriages soon get crowded. Reading is only a partial solution, for the monotonous(单调的) rhythm of the wheels clicking on the rails soon makes you sleep. During the day, sleep comes in snatches. While at night you rarely manage to sleep. Inevitably you arrive at your destination almost exhausted.

    Long car journey are even less pleasant, for it is quite impossible even to read. On motorways you can, at least, travel fairly safely at high speed, but more often than not, the greater span of the journey is spent on narrow, uneven roads which are crowded with traffic.

    By comparison, trips by sea offer a great variety of civilized comforts. You can stretch your legs on the broad decks, play games, swim, meet interesting people and enjoy good food-always assuming, of course, that the sea is calm. If it is not and you are likely to get seasick, no form of transport could be worse. Even if you travel in ideal weather, sea journeys take a long time. Relatively few people are prepared to sacrifice up to a third of their holidays for the pleasure of traveling on a ship.

    Airplanes have the reputation of being dangerous and a little expensive. But nothing can match them for speed and comfort. Traveling at a height of 30,000 feet and at over 500 miles an hour is a pleasant experience. For a few hours, you settle back in a deep armchair to enjoy the flight. The real relaxation can be a free film show and some other services. An airplane also offers you an unusual and breathtaking view of the world. You really see the shape of the land. If the landscape is hidden from the view, you can enjoy the extraordinary sight of unbroken cloud plains that stretch on for miles before you, while the sun shines brilliantly in a clear sky. The journey is so smooth that there is nothing to prevent you from reading or sleeping. However you decide to spend your time, one thing is certain: you will arrive at your destination fresh and untired.

Iman, the last Sumatran rhino(犀牛) in Malaysia, died in 2019 — bringing the endangered species one step closer to extinction. Now, Malaysian scientists are hoping to use tissues and cells from Iman and other dead rhinos to bring the population back.

"Before the three rhinos (the last survivors in Malaysia) died, we got their cells, and the cells are still alive — which is why I'm quite confident," Dr. Lokman said. "If we don't have any cells, or have just tissue that isn't living anymore, we wouldn't be able to do anything. But now we have a living thing that we can use. "

The cells came from the rhinos'hearts, lungs and brains. What is the most important is that the team collected stem cells (干细胞). One possible approach is to develop these stem cells into an egg (卵子) and sperm (精子), to create an embryo (胚胎) that will be placed into a surrogate mother (代孕母亲). She will likely be another rhino, either a Sumatran rhino from another country or another species. The other method is to take the egg of a surrogate animal, remove the nucleus (细胞核), and join it with a Sumatran rhino's body cell. This technique was famously used to clone Dolly the sheep in 1996. Dr. Lokman and his colleagues are trying both ways. The team is still in the early stages; next, they need to find a suitable surrogate female.

Sumatran rhinos are listed as critically endangered by the World Wildlife Fund. There are less than 80 alive in Indonesia and Thailand. The fall in the population was first caused by hunting. Later, the situation was worsened by the loss of habitats and human activity. Unfortunately, there are now only five remaining rhino species worldwide, and all are threatened. Some sub-species have already died out; the western black rhino was declared extinct in 2013. And it is a pity that the last male northern white rhino died in 2019.

Sugar-free cookies, sugar-free candy, and diet soda – are these better for you? After sugar became a no-no in the nutrition and wellness world, sugar-free food and drinks acted as a replacement for once beloved sweet drinks and snacks. Being claimed to be ZERO sugar means the food and drinks are healthier, better for diabetics, and help you slim down… Right? Wrong. Sugar-free products aren't better for you. In fact, they are worse. For most sugar-free products, it means that artificial sweeteners (甜味剂) are used instead of real sugar. The problem is that these sweeteners do not come from natural sources and they can do you more harm than good.

Let's get into what these artificial sweeteners actually are. Sugar-free sugar sounds wrong because there is no such thing as sugar-free sugar. Some of these sugar-free alternatives even contain sugar and the ones that have chemicals your body often does not know how to process. Most artificial sweeteners are a lot sweeter than sugar so only a small quantity of them are needed. That's why they can market sugar-free alternatives as "low-calorie" or "no-calorie". It also means that you get no nutritional value from consuming them, which is why so many sugar-free replacements are classified as "non-nutritive". These artificial sweeteners tend to hide under some names. Actually, they are 200-600 times sweeter than sugar.

When you eat sweet stuff, your body continues to desire it and, even though your body cannot metabolize (代谢) these sugar-free alternatives, your brain does not know the difference. In turn sugar-free alternatives relate to weight gain and Type-2 diabetes. Besides, artificial sweeteners also damage your gut's ability to break down sugar which impacts everything you eat. In other words, your body doesn't know how to handle artificial sweeteners because they have nothing real to process.

Here is a good rule of thumb: stay away from artificial sweeteners and look for non-sugar, natural sweeteners like stevia (甜叶菊) or date sugar. In the war against artificial sweeteners and real sugar, both lose. Satisfy your sweet tooth with natural sugar that comes from fruits and stay away from products claimed to be sugar-free.