Writing it down

    Unlike some other European languages, English is a little tricky when it comes to writing. How a word is pronounced and how it is actually spelt can be very different things.

    Same spelling, different meanings

Imagine, then, a situation where two words are spelt and pronounced exactly the same way, but have completely different meanings. Welcome to the world of homonyms（同形同音异义词）. Take, for example, the word "fair"—it can be a kind of festival, an adjective to describe the colour of your hair or how you should play a game. Or "leg", which can be attached to a person, or a table and can also be a distance you travel, or a part of a competition.

Don't take it literally（字面意思）

So how do you know which meaning someone is referring to? You don't, except by the context. Obviously, if someone asks you to "give them a hand", they don't want you to remove what is at the end of your arm.

What's in a name?

    Sometimes even the context doesn't help much—the result can be amusing. These sentences play with the double meaning of a noun:

    Sentence 1: I used to be a banker, but I lost interest.

Sentence 2: A small boy swallowed some coins and had to go to hospital. When his grandmother phoned to ask how he was, the nurse said: "No change yet".

    More ambiguity（歧义）

    Sentence 3 plays with the different meanings of a verb:

    Sentence 3: I wondered why the ball was getting bigger. Then it hit me.

Double trouble

    And sometimes a word can be a noun and a verb, but have different meanings. Can you work this one out?

    Sentence 4: Time flies like an arrow. Fruit flies like a banana.

    If you like these homonyms, you will be pleased to know that English has plenty more!

    It's true that many dads in the wild aren't interested in parenting, but there are some that work pretty hard to give their little ones a good start. Maybe one of these dads will make you remember your own dad!

    The male giant water bug (雄性负子蝽) doesn't seem to mind a heavy load (负荷物) on his back for his kids. The female puts about 100 to 150 eggs on the back of the male, and then she leaves. Once the female is gone, the male has to look after the eggs. It usually takes one to two weeks for the eggs to hatch (孵化). The father giant water bug jumps around to make sure the growing eggs get enough air and water. All this time he can't fly because of the weight of the eggs growing rapidly on his back.

    Now let's turn to the male stickleback fish. When the mother leaves after laying her eggs, the father tends his young. If the young fish go too far away, their father helps with their safe return by carrying them back in his mouth. The male stickleback looks after all his young — as many as 100 — until they can live on their own.

A similar example can be found in emperor penguins (帝企鹅) living in cold areas. The male emperor penguin goes without food while looking after his egg until it hatches. For about 62 to 67 days, the egg stays on top of the father's feet, in very cold temperatures that drop down to -39℃. As a result, the father may lose nearly 50 percent of his body weight while waiting for his baby penguin to be born!

    It happens from time to time: you feel terrible when you take your first bite of a certain food, but after eating more, you find yourself enjoying it. This is what is called an acquired taste. But why do our tastes change?

    The answer, according to a recent study presented at an American Chemical Society meeting in Boston, lies in proteins in our saliva (唾液).

    Most of us tend to think saliva, almost entirely made up of water, is “only a mouth lubricant (润滑剂) helping us to swallow food,” the New York Times said. However, it also contains many proteins, which can help break food down, protect our teeth and help in tasting food.

    To explain how these proteins affect taste, a team of scientists from Purdue University in the US invited 64 volunteers to drink a bitter-tasting chocolate milk three times a day for six weeks and rated their tastes at the same time.

    According to the research, the participants found a strong bitterness on the first day, but the unpleasant flavor came to decrease as time went on and finally disappeared.

    That is not all that was changing. A noticeable increase in the levels of proline-rich (富含脯氨酸的) proteins was found in the saliva samples of the test subjects in the research period. These proteins serve to reduce the bitterness we taste and improve our adaptation to this flavor.

    “We think the body adapts to reduce the negative feeling of these bitter compounds,” said Cordelia Running, a food scientist at Purdue University. “Saliva changes flavor, which in turn changes eating choices.”

    This change in taste not only makes the food tastier, but also helps people keep an appetite for healthy food whose flavor might otherwise keep them away.

    One day, these proteins may even be extracted (提炼) and used as a separate food additive that could help people stick to healthy food whose flavor they continue to dislike, researchers told Science Alert. And according to Running, even it doesn't happen, the idea that “maybe some little piece of your body is actually trying to help you” could really benefit some people. Let's wait and see.

    It's common knowledge that some countries have higher life expectancies than others, but the city you live in can also affect your health.

    Some cities are hard on their residents. In places with poor city planning, for example Lagos, which was called out recently by the Economist Intelligence Unit, public spaces are few, making outdoor activities hard. Lack of infrastructure (基础建设) blocks the streets with cars and the air with pollutants, and residents work long hours for little money.

    These are just some of the factors added up by Spotahome, a rental agency. They've analyzed data from a range of sources, including the World Health Organization, TripAdvisor and the CIA World Factbook to score each city on health, gym availability and quality, life expectancy, obesity, green space and other elements to make a list to work out which are the world's healthiest cities.

    The list is certainly Euro-centric and sunshine is seen as a positive factor. It does go some way towards suggesting which cities are getting it right in providing a good life for their residents. It may not be surprising to learn that most of the healthiest cities are in northern Europe, known for its people-first approach to city planning. The cities of Australia and Canada also do well. However, the first American city is only in 34th place. The UK doesn't fare too well either-its only city in the top 50 list is London, in 40th.

    Whether you're planning a wholesome holiday, or simply wondering what your city can do better in its quest for happy citizens, the list of the 50 healthiest cities will give you pause for thought about the future of city planning. Here are the slender, healthy-eating, clean-aired cities that are getting it right.

    One family, which moved from Japan and settled at the turn of the century near San Francisco, had built a business in which they grew roses and trucked them into San Francisco three mornings a week.

    The other family also marketed roses. For almost four decades the two families were neighbors, and the sons took over the farms, but then on December 7, 1941, Japan attacked Pearl Harbor. Although the rest of the family members were American, the father of the Japanese family had never been naturalized. As they planned to leave the country, his neighbor made it clear that, if necessary, he would look after his friend's nursery (花圃). It was something each family had learned in church-Love the neighbor as themselves. "You would do the same for us," he told his Japanese friend.

    It was not long before the Japanese family was transported to a poor landscape in Canada. A full year went by. Then two. Then three. While the Japanese neighbors were in Canada, their friends worked in the greenhouses. Sometimes the father's work could stretch to 16 and 17 hours. And then one day, when the war in Europe had ended, the Japanese family packed up and boarded a train. They were going home.

    What would they find? The family was met at the train station by their neighbors, and when they got to their home, the whole Japanese family were shocked. There was the nursery, complete, clean and shining in the sunlight, neat, prosperous and healthy. And the house was just as clean and welcoming as the nursery. And there on the dining room ground was one perfect red (玫瑰花蕾), just waiting to unfold-the gift of one neighbor to another.

    Andrew Ritchie, inventor of the Brompton folding bicycle, once said that perfect portable bike would be "like a magic carpet... You could fold it up and put it into your pocket or handbag". Then he paused: "But you'll always be limited by the size of the wheels. And so far no one has invented a folding wheel."

It was a rare — indeed unique — occasion when I was able to put Ritchie right. A 19th-century inventor, William Henry James Grout, did in fact design a folding wheel. His bike, predictably named the Grout Portable, had a frame that was divided into two and a larger wheel that could be separated into four pieces. All the bits fitted into Grout's Wonderful Bag, a leather case.

    Grout's aim: to solve the problems of carrying a bike on a train. Now doesn't that sound familiar? Grout intended to find a way of making a bike small enough for train travel: his bike was a huge beast. And importantly, the design of early bicycles gave him an advantage: in Grout's day, tyres were solid, which made the business of dividing a wheel into four separate parts relatively simple. You couldn't do the same with a wheel fitted with a one-piece inflated(充气的) tyre.

    So, in a 21st-century environment, is the idea of the folding wheel dead? It is not. A British design engineer, Duncan Fitzsimons , has developed a wheel that can be folded into something like a slender ellipse(椭圆). From beginning to end, the tyre remains inflated.

    Will the young Fitzsimons's folding wheel make it into production? I have no idea. But his inventiveness shows two things. First, people have been saying for more than a century that bike design has reached its limit, except for gradual advances. It's as silly a concept now as it was 100 years ago: there's plenty still to go for. Second, it is in the field of folding bikes that we are seeing the most interesting inventions. You can buy a folding bike for less than £1,000 that can be knocked down so small that can be carried on a plane ——minus wheels, of course ——as hand baggage.

    Folding wheels would make all manner of things possible. Have we yet got the magic carpet of Andrew Ritchie's imagination? No. But it's progress.