Since English biologist Charles Darwin published On the Origin of Species in 1859, scientists have vastly improved their knowledge of natural history. However, a lot of information is still of the speculation, and scientists can still only make educated guesses at certain things.

    One subject that they guess about is why some 400 million years ago, animals in the sea developed limbs (肢) that allowed them to move onto and live on land.

    Recently, an idea that occurred to the US paleontologist (古生物学家) Alfred Romer a century ago became a hot topic once again.

    Homer thought that tidal (潮汐的) pools might have led to fish gaining limbs. Sea animals would have been forced into these pools by strong tides. Then, they would have been made either to adapt to their new environment close to land or die. The fittest among them grew to accomplish the transition (过渡) from sea to land.

    Romer called these earliest four-footed animals “tetrapods”. Science has always thought that this was a credible theory, but only recently has there been strong enough evidence to support it.

    Hannah Byrne is an oceanographer (海洋学家) at Uppsala University in Sweden. She announced at the 2018 Ocean Sciences Meeting in Oregon, US, that by using computer software, her team had managed to link Homer's theory to places where fossil deposits (沉积物) of the earliest tetrapods were found.

    According to the magazine Science, in 2014, Steven Balbus, a scientist at the University of Oxford in the UK, calculated that 400 million years ago, when the move from land to sea was achieved, tides were stronger than they are today. This is because the planet was 10 percent closer to the moon than it is now.

    The creatures stranded in the pools would have been under the pressure of “survival of the fittest”, explained Mattias Green, an ocean scientist at the UK's University of Bangor. As he told Science, “After a few days in these pools, you become food or you run out of food... the fish that had large limbs had an advantage because they could flip (翻转) themselves back in the water.”

    As is often the case, however, there are others who find the theory less convincing. Cambridge University's paleontologist Jennifer Clark, speaking to Nature magazine, seemed unconvinced. “It's only one of many ideas for the origin of land-based tetrapods, any or all of which may have been a part of the answer,” she said.

    We just love giving cards in Britain. If there's a special occasion coming up, there's no doubt that we'll be there, card in hand, to celebrate it. And this isn't just for birthdays; we also give cards when people are ill or when they have got a new job. And even if you forgot somebody's birthday, there are even "sorry it's late" cards. So you can pretty much find a card for any occasion.

    Before coming to Italy I had never even considered that our love for card giving might not be shared by other countries. In fact, my workmates told me that hardly anyone sends Christmas cards in Italy and that they actually don't really give birthday cards either! Unbelievable! In the UK, if a close friend or family member didn't get me a card I'd feel upset! However, the only place you can buy cards in Italy is in a shop which sells school things. In comparison, we have whole shops that sell them in the UK and we even have different types of card shops.

    Although cards can take up your time, from choosing the perfect one, to thinking up the personal message inside, I think it's a really nice gesture. And especially with Christmas cards, it adds to that festive feeling. When I sit down to write countless cards to friends and family, I get that little bit happier that it will be Christmas soon! Especially when I see my own Christmas cards, proudly sitting on my desk wishing me a very merry Christmas.

    Of course, the problem comes when they're no longer needed, when Christmas is over. It makes me sad just to throw them all away, so I try and hang on to my favorite ones.

    We may think we're a culture that gets rid of our worn technology at the first sight of something shiny and new, but a new study shows that we keep using our old devices（装置）well after they go out of style. That's bad news for the environment – and our wallets – as these outdated devices consume much more energy than the news ones that do the same things.

    To figure out how much power these devices are using, Callie Babbitt and her colleagues at the Rochester Institute of Technology in New York tracked the environmental costs for each product throughout its life – from when its minerals are mined to when we stop using the device. This method provided a readout for how home energy use has evolved since the early 1990s. Devices were grouped by generation. Desktop computers, basic mobile phones, and box-set TVs defined 1992. Digital cameras arrived on the scene in 1997. And MP3 players, smart phones, and LCD TVs entered homes in 2002, before tablets and e-readers showed up in 2007.

    As we accumulated more devices, however, we didn't throw out our old ones. "The living-room television is replaced and gets planted in the kids' room, and suddenly one day, you have a TV in every room of the house," said one researcher. The average number of electronic devices rose from four per household in 1992 to 13 in 2007. We're not just keeping these old devices – we continue to use them. According to the analysis of Babbitt's team, old desktop monitors and box TVs with cathode ray tubes are the worst devices with their energy consumption and contribution to greenhouse gas emissions（排放）more than doubling during the 1992 to 2007 window.

    So what's the solution? The team's date only went up to 2007, but the researchers also explored what would happen if consumers replaced old products with new electronics that serve more than one function, such as a tablet for word processing and TV viewing. They found that more on-demand environment viewing on tablets instead of TVs and desktop computers could cut energy consumption by 44%.

    Learning any language is hard, but learning English can be especially challenging. Why? Because native speakers use the language in ways that textbooks could never describe. In particular, words that British people use cause many language students to scratch(JT) their heads.

    Here's an example: You happen to hear a Briton calling someone a “wazzock”. But what exactly is a wazzock? This word, in fact, means a foolish person, although there's nothing about it that would help you guess that. There are many strange terms like this in British English - the Oxford English Dictionary would be much smaller without these strange usages filling its pages.

    How can these odd words be explained? Part of the answer is the British sense of humor. Britons don't like to take things too seriously, and this is evident through many British words and phrases. For example, to spend a penny means to use the bathroom. It refers to the days when people had to pay a penny to use a public toilet.

    In an interview for the BBC's website, British linguist David Crystal suggested there may be historical reasons for the sheer number of odd words and phrases in British English. He thinks that they began in the late 16th and. early 17th centuries. This was a great age for the theatre, when Shakespeare and other writers worked hard to keep up with the demand for new plays. The theatre's popularity also created an incentive (刺激) to invent new words.

    With this in mind, perhaps Shakespeare and his peers are to blame for unusual British words such as “codswallop” and “balderdash”—which both, ironically, mean nonsense.

    While these strange words may be confusing to non-native speakers, they certainly make studying English a lot more interesting.

    Many of us love July because it's the month when nature's berries and stone fruits are in abundance. These colourful and sweet jewels form British Columbia's fields are little powerhouses of nutritional protection.

    Of the common berries, strawberries are highest in vitamin C, although, because of their seeds, raspberries contain a little more protein (蛋白质), iron and zinc (not that fruits have much protein). Blueberries are particularly high in antioxidants (抗氧化物质). The yellow and orange stone fruits such as peaches are high in the carotenoids we turn into vitamin A and which are antioxidants. As for cherries (樱桃), they are so delicious who cares? However, they are rich in vitamin C.

    When combined with berries of slices of other fruits, frozen bananas make an excellent base for thick, cooling fruit shakes and low fat "ice cream". For this purpose, select ripe bananas for freezing as they are much sweeter. Remove the skin and place them in plastic bags or containers and freeze. If you like, a squeeze of fresh lemon juice on the bananas will prevent them turning brown. Frozen bananas will last several weeks, depending on their ripeness and the temperature of the freezer.

    If you have a juicer, you can simply feed in frozen bananas and some berries or sliced fruit. Out comes a "soft-serve" creamy dessert, to be eaten right away. This makes a fun activity for a children's party; they love feeding the fruit and frozen bananas into the top of the machine and watching the ice cream come out below.

Foldable phones are once again facing questions about their durability(耐久性).The Galaxy Z Flip and the Motorola Razr are now both available to buy in the US-but early reports suggest the screens are easily damaged.

One media published photos of two layers of the Razr's display separating, affecting the touch screen. The Galaxy flip, meanwhile, boasts(自夸)a "flexible glass" display—but tests appear to show it scratching(刮擦)as easily as plastic.

In a statement, Samsung said the display had a protective layer, and had undergone extensive testing. "While the display does bend, it should be handled with care, "it said.

The Z Flip's "pretty thin glass" is one of Samsung's primary marketing messages for the new phone. But a durability test conducted by popular Zack Nelson, a regular buyer, suggested it was no more durable than soft plastic screen, and could even be dented(痕)by fingernail.

Nelson said Samsung's screen scratched exactly how plastic screen would react. "I don't know what material this is, but Samsung definitely shouldn't be calling it glass," he said. He found that the screen of the Motorola Razr scratched as easily but it is not marketed as "glass".

The Motorola Razr was put on sale 13 days ago in the US, but Raymond Wong, an editor says the flexible screen on his handset has already broken. The upper layer of the Razr's screen separated from the bottom, creating "a giant horizontal air bubble" for no apparent reason. He wrote that the fault appeared after 45-minute train ride during which the phone was in his pocket. The screen was completely warped from hinge-to-hinge with the top layer raised like a poorly applied screen protector. But Mr. Wong said that apart from the visual problem, the damage has affected the responsiveness of the touchscreen.