Most people will tell you that without a cup of coffee in the morning, they cannot function. Coffee is a good drink when consumed in right amount. 【小题1】

A legend says that Kaldi, an Ethiopian, discovered his goats enjoy eating coffee plants. Curious, he tasted the leaves and began to dance around. A passing monk witnessed the scene and took some back to his fellow monks. Later that night, the monks experienced extreme inspiration. 【小题2】 Soon Arabia started roasting coffee beans. By 1000 A.D., Muslims were drinking coffee to stay awake. A merchant from Venice introduced coffee to Europe in 1615. By 1696, the Dutch started growing the coffee bush in Java. By 1723, coffee plants were introduced to the Americas. Today, coffee is the most popular drink in the world.

Caffeine is the major chemical in coffee. Caffeine poisoning can occur if more than 400 milligrams of caffeine is drunk in a short period, which is about four to five cups of coffee. 【小题3】 So it should be avoided before bed.

【小题4】 Studies have shown that it helps cognitive skills in elderly women. Women who drank three cups of coffee daily scored higher on memory tests than women who drank one cup of coffee.

Large amounts of coffee can cause nervousness, worries and heartburn. However, if mixed with milk, it is fine. 【小题5】 The more you drink, the more you depend on it. For some people, just one cup of coffee a day is OK.

Humans spend approximately one-third of their lives sleeping, which means that by the time you reach 15 years old, you will have slept for about 5 years! However, the question remains: why do we do it? Sleep has long been a puzzle for people, leading scientists to explore its mysteries. They have found that during sleep, our brains and bodies do not simply shut down; instead, complex processes unfold.

What causes sleepiness? It’s caused by our biological clock releasing a special chemical signal at the same time daily, signaling it’’s time to wind down. The feeling of heaviness comes from the buildup of old nerve messenger chemicals. When the message gets too much, the brain senses that it’s time to sleep. During sleep, the body breaks down and clears away these old messengers, preparing for a fresh start.

As you slip into sleep, your heart and breathing slow down, and your brain ignores the most sounds and surroundings around you. Despite appearances, your brain remains active during sleep, performing essential tasks. Throughout the night, you cycle through light, deep, and REM (rapid eye movement) sleep stages every 90 minutes. Early on, slow-wave sleep is the primary stage, aiding in brain cleaning, while towards morning,REM sleep increases, leading to vivid dreams. During sleep, your body repairs and grows, creating new skin, muscle, and other tissues with released chemicals. It’s also a time for hormone (荷尔蒙) production, aiding growth, and boosting the immune (免疫) system to fight infections.

Scientists still have many questions about sleep, such as why some people need more sleep than others and how certain animals can function with less sleep. They aim to find ways to improve sleep quality. However, one thing is clear: getting enough sleep is vital for health and intelligence. Think of sleep as a free magic potion that strengthens you, aids growth, boosts immunity, and enhances intelligence, happiness, and creativity. Simply lie down and rest to enjoy these benefits.

While staring out of the window during a flight, not everyone will think carefully about the question why airplanes have rounded windows rather than square ones .

Over the years, aerospace engineering has made huge steps in airplane technology, meaning planes can carry more passengers and go faster. The planes have also changed shape to increase safety—including the windows. As commercial air travel took off in the mid -20th century, airline companies began to fly at higher altitudes to lower their cost—the air density (密度) is lower up there, creating less drag (阻力) for airplanes. However, higher altitudes came with problems, like the fact human beings can’t really survive at 30,000 feet. To make that possible, the cabin was changed to a cylindrical (圆柱体) shape to support the pressure inside. But at first, plane builders left in the standard square windows and this expansion meant disaster. The de Havilland Comet came into fashion in the 1950s. With a closed cabin, it was able to go higher and faster than other aircraft .

However, where there’s a comer, there’s a weak spot. Windows, having four comers, have four potential weak spots, making them likely to crash under stress— such as air pressure. By curving the window, the stress that would eventually break the window comer is distributed and the chance of it breaking is reduced. Rounded shapes are also stronger and resist deformation   (变形), and can thus survive the extreme differences in pressure between the inside and outside of the aircraft .

Fortunately, designers figured out the lack of design pretty quick . Now we have nice, rounded airplane windows that can resist the pressure of traveling altitude. It gives being able to gaze out of your window to the world from 35,000 feet a whole new outlook, doesn’t it?