Here, sleep experts clear up some of the biggest misunderstandings about sleep they see with their patients, which could weaken your ability to have a night of good sleep.

Myth: {#blank#}1{#/blank#}

    The latest research shows that the right amount of sleep may vary from person to person and should leave you feeling energized the next day. I'm a sleep doctor. Take myself for example. {#blank#}2{#/blank#}.

Myth: Don't fall asleep with the TV on.

    I've cured more people suffering from sleep problems than you can imagine by telling  people it's OK to fall asleep with the TV on. {#blank#}3{#/blank#}Control the watching time so it doesn't affect your sleep later in the night.

Myth: You can catch up on lost sleep on the weekend.

    {#blank#}4{#/blank#} A Harvard study found that even if you sleep for an extra 10 hours on the weekend to make up for only sleeping six hours a night for two weeks, those extra hours won't improve  your reaction times or ability to focus. Plus, sleeping late throws off your biological clock, which can lead to obesity, diabetes, and heart disease.

Myth: Alcohol can help you rest easy.

    {#blank#}5{#/blank#} Alcohol may relax you so you nod off quicker, but studies show you'll wake up more and get less of deep sleep you need to feel rested.

    Summer is the season to dive into new activities and relax. And right now is the time to make sure that you're ready for the great outdoors, the holiday planning and travel, and the bathing suit beach days.

    If you want to lose weight before summer, concentrate on dropping no more than a pound or two a week.{#blank#}1{#/blank#} And when you trouble yourself, sooner or later you，re going to gain it back. Operate on a 500-calorie-a-day deficit (亏损).{#blank#}2{#/blank#} So if you cut 500 calories a day for seven days straight, you'll lose a pound a week right there.

    Operating at a decrease of 500 calories a day should involve both eating less and moving more. For example, you could consume 300 fewer calories and bum 200 extra per day.

    Include both healthy eating and exercise in your weight-loss plan, and break the 500-calorie goal into small groups to make it more reachable.{#blank#}3{#/blank#}

    To cut 100 calories:{#blank#}4{#/blank#} Have vegetable pizza instead of pepperoni (意大利辣香肠). Use our Nutritional Needs Calculator to determine how many daily calories you should consume in order to lose, gain, or maintain your healthy goal weight. Once you've reached your goal, recalculate your nutritional needs for keeping extra weight off all summer long.

    To burn 100 calories: spend 15 minutes biking. {#blank#}5{#/blank#} Spend 20 minutes gardening. Keep on exercising at least 30 minutes daily a week. Reading food labels and counting calories or writing down what and when you eat can give you more control as well.

A. Here are some simple ways to get there.

B. Walk or run one mile.

C. A pound is 3,500 calories.

D. It is okay to have some snacks between your meals.

E. You should always make sure you get a lot of sleep.

F. Anything more than that usually means you're troubling yourself.

G. Eat a chicken breast without the skin.

    How cool can libraries be in an era(时代) of iPods and Kindles? More than you think. Only if you know where to go.

Central Library: Seattle, Washington, United States

    The Central Library in Seattle is modern and fashionable and has tourists from around the world paying visits and taking tours. It was designed by Dutch architect Rem Koolhaas and American designer Joshua Prince-Ramus. Tours began in 2006, two years after its opening. The library holds various art exhibitions, book signings and other events, while visitors can stop by the Chocolati cat for a coffee and scan through the gift shop anytime.

Trinity College Library: Dublin, Ireland

    The Trinity College Library in Dublin is the oldest library in Ireland, founded in 1592 by Queen Elizabeth I. It is the largest single library in the world, also known as the Long Room, which contains more than 200,000 of the library's oldest books. The Long Room houses one of the oldest harps(竖琴) in Ireland. Dating to the 15^th century, the old harp is the model for the symbol of Ireland.

Geisel Library, University of California: San Diego, United States

    At first glance, it looks like a spaceship. Architect William Pereira, who helped design actual space launch facilities at Cape Canaveral in Houston, Texas, designed the library in 1970. It has been featured in sci-fi films, short stories and novels. The library hosts “Dinner in the Library” which invites readers for cocktails, and also a special speech from distinguished authors.

TU Delft Library: The Netherlands

    The library at the Delft University of Technology was constructed in 1997 and has more than 862,000 books, 16,000 magazine subscriptions and its own museum. The building itself exists beneath the ground, so you can't really see the actual library. What makes it interesting is the roof, which is a grassy hill. The roof covers 5,500 square meters. And it has become one of the most striking and greenest structures in the area.

    Next time you hear a funny joke you'd better not laugh too hard. According to a paper published by the British Medical Journal, laughter isn't always the best medicine. Sometimes it can even be harmful. Professor Robin Ferner from the University of Birmingham, one of the authors of the study, found that bad things could happen to people who laughed too much. He says, "We found people with heartbeat problems which had stopped their hearts, we found people who had fainted(昏倒), and we found people who'd dislocated their jaws or burst their lungs."

    It seems that laughing can be no laughing matter. But it's not all doom and gloom. Professor Ferner says there are benefits to laughing when you want to lose weight, for example. Yes, that's right: laugh and be slimmer! Professor Ferner explains that: "You use energy when you laugh, you move your diaphragm(横隔膜), you expand your lungs, and both those things can be helpful."

    According to the research, laughing for a quarter of an hour can burn 40 calories, and if you laughed all day you'd use about 2, 000 calories, which is what most people consume in a day. But don't do that or you might end up with a painful jaw. Ouch! Or you might find people looking at you in a funny way.

    But I don't want to finish this article leaving you feeling desperate. Laughter comes naturally for most of us. Babies begin to laugh at around 3-6 months. So give in to your sense of humour and keep smiling. Life is short anyway.

    Walk down any British shopping street and you will find shops with strange names. Why is the opticians (眼镜店) called "Eyediology"? And who decided to name the butchers (肉铺) "Meat you there" ? What's going on?

    Puns are jokes based on words that sound the same. You've probably noticed that many words in English which are spelt in different ways and have different meanings are pronounced in the same way. Think about the name of the restaurant: "plaice" is a kind of fish so our restaurant is "the place" to eat fish. Butchers sell meat – so we'll "meet you there" – and opticians look after our eyes in a scientific way – so eyed – iology (ideology) is a name that fits. Hairdressers shear (cut) your locks (hair) and comb it – say the three words together quickly and you have the name of a famous detective. In shop titles and adverts, puns are used to get our attention.

    Puns are very old. The ancient Egyptians and Romans liked to pun. Shakespeare uses many puns in his plays – King Richard the Third (the son of York) brings "glorious summer" – just think about a word that has the same sound as son.

    Many people enjoy a good pun (pun / fun for all the family!) – others hate them. Puns aren't really designed to make you laugh. Here are some puns that might leave you asking for no more puns please. Have you heard about the bears who voted in the North Poll? Or the cheetah (印度豹) who couldn't be trusted at cards? Or how about the clever little Australian animal that had lots of koalaifications or the camel (骆驼) with no humps (驼峰) that was called Humphrey (and so was free of humps...)

    Puns can be funny but they sometimes make important points. Here's a fashion tip: "skinny genes make skinny jeans": so don't worry if your jeans don't fit. Look at your parents!

Round and Round They Go

Space is becoming more crowded. On December 3, a Falcon 9 rocket made by SpaceX thundered into the sky. On board were 64 small satellites, more than any American company had launched before in one go. They have a variety of uses, from space-based- radar to the monitoring of radio-frequency- emissions.

These objects are part of the latest breed of low-Earth-orbit (LEO) satellites. This launch is just taste of what is planned. SpaceX and OneWeb, a communications firm, plan to launch satellites in their thousands, not hundreds. The pair are set to double the total number of satellites in orbit by 2027.

That promises to change things dramatically on Earth. LEO satellites can bring internet connectivity to places where it is still unavailable or unaffordable. This will also be a lasting source of new demand for the space economy. Morgan Stanley, a bank, projects that the space industry will grow from $350 billion in 2016 to more than $1. I trillion by 2040. New internet satellites will account for a half this increase.

For that to happen, however, three worries must be overcome. Debris(碎片)is the most familiar concern. As long ago as 1978, Donald Kessler, a scientist at NASA, proposed situation in which, when enough satellites were packed into low-Earth orbits, any collision could cause a chain reaction which would eventually destroy all space craft in its orbital plane(平面). The syndrome which bears Mr. Kessler's name weighs heavily on the minds of executives at the new satellite firms. Debris could cause entire tracts(广阔的一片) of space to be unusable for decades.

Solutions exist. One is to grab malfunction satellites and pull them down into Earth's atmosphere. Another is to monitor space more intensively for debris; a US Air Force programme called Space Fence is due to start in 2019. But technology is only part of the answer. Rules are needed to govern the safe disposal(清除) of old satellites from low-Earth orbit. The United States' Federal Communications Commission is revising its regulations with this in mind. Other countries should follow suit.

Cyber-security is a second, long-standing worry. Hackers could take control of a satellite and seal intellectual property, redirect data flows or cause a collision. The satellite industry has been slow to respond to such concerns. But as more of the world's population comes to rely on the infrastructure of space for access to the internet, the need for action intensifies.

The third issue follows from the first two. If a simple mistake or a cyber-attack can cause a chain reaction which wipes out hundreds of billions of dollars of investment, who is liable? Underwriters(保险商) are studying the plans of firms that wish to operate large numbers of satellites. But there is a long way to go before the risks are well understood, let alone priced.

As space becomes more commercialized mind-bending prospects open up: packages moved across the planet in minutes by rocket rather than by plane, equipment sent to other small planets, passengers launched into orbit and beyond. All that and more may come, one day. But such activities would raise the same questions as LEO satellites do. They must be answered before the space economy can truly develop.