1 . The text from my son said it all: “Dad, there’s an article you were born to write that the world is finally ready for: Bring Back the Handkerchief!” As my son knows, there’s no “bring back” for me. For me, the handkerchief never left.

My mother raised me with several fixed rules. One was that a gentleman always has a clean handkerchief in his right rear pocket, a piece of simple cotton, roughly 15 inches square and less than four inches when folded. I was a dutiful son, but as a child, I had been wondering what it was there for. After 60 years, my body weight now feels wrong if I’m heading out of the house with an empty back pocket.

I am sure this habit has sometimes struck friends but in polite company nobody comments on somebody else’s business. Children like my kids think of my hankie ridiculously old-fashioned and they have their arguments. If you have to be prepared every day for allergies or a cold, why not choose a little packet of tissues, which saves you from that disgusting business of blowing your nose in the thing and then stuffing it back in your pants?

Point taken. But a handkerchief is more durable and has a far wider variety of uses. Can you grab the handle of a pot that’s boiling over with a Kleenex? Or do you recall the cases of skinned knees and drippy noses that hankie wiped? In fact, my wife gave me several new handkerchiefs as gifts. Neither of us can count the number of times her eyes have welled up at a movie, or, as happens, she’s needed to blow her nose.

Yet not even my mother could have anticipated the hankie’s new role as an Essential Public Health Appliance. All of us have learnt how hard it is to follow advice from medical experts about not touching your face. Here is an answer. Use your hankie. In case of emergency, your handkerchief can become a makeshift DIY mask that can be pulled over your lower face like a robber entering a bank.

And it will certainly give me the chance to lift my chin and look at my adult children through one eye, asking in her good-hearted way, “What do you have to say now, smarty-pants?”

Visitors have flocked from far and wide     1     (visit) the world’s largest ice and snow festival dubbed (称为) “Disneyland on ice” recently. This is China’s Harbin International Ice and Snow Sculpture Festival — a family friendly, fun-filled dream land     2     (fill) with intricately designed ice sculptures. Although visitors are treated     3     masses of ice sculptures throughout Harbin City, Sun Island and Ice and Snow World, are the two main areas. Ice and Snow World area is largely open at night, and     4     (feature) illuminated ice skyscrapers. This year, they’ve also added such a towering snowflake Ferris wheel     5     visitors can take in the     6     (complete) of this impressive winter wonderland from the air. The festival has established     7     (it)as one of the best winter celebrations worldwide, and has been pulling in an estimated 28.7 billion yuan per year.

One travel guide said: “I’ve always had     8     difficult time with winter, or at least the idea of it. I’ve associated winter with misery, irrespective of how I     9     (physical) react to the cold, and have gone to great     10     (length) to deny its very existence. But exploring China’s Harbin Ice and Snow Festival brought me indescribable joy.”

3 . “THE ANT AND THE ZEBRA” sounds like the title of a Aesop’s fable. Like all good fables, this one has a moral, which is that tinkering with nature has unpredictable consequences. Unlike the Greek originals, though, this fable is real.

The story plays out in Laikipia county, Kenya. The characters include big-headed ants, an invasive species, the native acacia ants, these invasive ants have gradually been replacing, the whistling-thorn trees where both sorts of ants live, a cast of elephants, lions, zebras and buffalo, and Douglas Kamaru, a Kenyan biologist in the University of Wyoming. As Mr Kamaru reports this week in Science, the ant invasion has set off a complicated chain of consequences which has helped zebras at the expense of buffalo — thus illustrating a phenomenon called “trophic cascade”.

It works like this. Whistling-thorns have co-evolved with the local ants. The trees provide the ants with shelter and food, in the form of large, hollow thorns into which they produce nutritious nectar. The ants, meanwhile, protect the trees by seeing off the chief threat to them, the local elephants, which are not keen to feed on trees crawling with biting insects.

Acacia ants’ habitat are thickly carpeted with whistling-thorns. Big-headed ants, however, are not good at keeping the elephants at bay. The elephants move in and bite the trees, removing much of the area’s cover. That upsets the local lions, which often use this cover to hide when hunting zebra. To compensate, the lions switch to hunting buffalo, which are more dangerous, but less fleet of foot.

Mr Kamaru has put numbers to the process, too. In invaded areas, elephants break trees five to seven times as often as in uninvaded ones. And in those uninvaded places, zebra kills are almost three times as frequent as in the invaded ones. Indeed, between 2003 and 2020, as the big-headed ants have spread, the percentage of local lion kills where the victims was a zebra fell from 67% to 42%. Over the same period, the percentage of kills that were buffalo rose from zero to 42%. Whether the buffalo blame the ants for their misfortune, no one knows.

8 . Every Friday night the Chevron gas station food mart offers a discount on the leftover food. To ensure the best selection, my mother and I pile into our old car and _________ in front of the mart at five p. m. sharp, ready to get our _________.

Chevron shopping _________ like this: One day my mother suddenly realized that she had maxed out (透支) almost every credit card except the Chevron card and we needed groceries for the week. Since our first _________ there, I’ve learned to believe in flexibility. In my life, it has become necessary to _________ the idea of grocery shopping. My mother and I can no longer shop at real grocery stores, _________ we still get the necessities.

Grocery shopping at Chevron has its _________. The worst is when we have so many items that it takes the cashier what seems like hours to ring up everything. A line of _________ customers formed behind us. It’s that line that _________ the most-the way they look at us. My mother never notices — or maybe she __________ not to.

I’m __________ to shop there, and I’m afraid of running into someone I know. I once expressed my fear of being seen shopping at Chevron to my mother, and her eyes shone with disappointment. I know that I hurt her feelings when I try to __________ our weekly shopping trips.

And that is why I hold on to the idea of __________ so tightly. Whenever I feel the __________ rise to my face, I remind myself at this point in my life I am struggling does not mean that I will always struggle. I know that whatever happens, we will always __________ a way to survive.

9 . If you want to make a good first impression in that important business meeting, it is no longer about wearing the sharpest suit or the firmest handshake but about making sure that the little Zoom window with your face in it projects professionalism. But this isn’t always easy.     1     Here are some tips.

• Don’t hold your phone.

If you absolutely must join the meeting on your phone, then don’t hold it in your hand.     2     Your colleagues won’t see your picture swinging about wildly. And the camera won’t suddenly look up your nose when you naturally pull your phone closer to your face.

•     3    

How the light falls on our faces counts. So make sure that you don’t have a big, direct source of light behind you, because all it will do is make your face dark and hard to see — and that’s the most important part!

• A professional microphone makes up for bad video.

The built-in microphones inside our computers can be pretty good, but they’re never truly great.     4     What matters is that people should be able to hear what you’re saying.

• Don’t rely on the default (默认) camera.

    5     This could help create the illusion of eye contact. However, this isn’t always easy, especially if you’re using a laptop and are sitting at a desk, towering above it. It might be worth getting an external camera you can put on top of a monitor.

10 . With the fast development of astronomy, astronomers are eager to find a hint of the familiar: planets that resemble Earth. By pushing technology to the limits, astronomers are rapidly approaching the day when they can find another Earth.

The most direct approach is to take a picture of it with a telescope. However, a more effective way is to use “the Doppler technique”. This involves analyzing starlight for evidence that the star’s movement is affected by the gravitational pull of a planet. Nowadays, astronomers can tell when a planet is pulling its star by only one meter a second — about human walking speed. That’s enough to detect a giant planet in a big orbit, or a small planet if it’s close to its star.

Another approach is to watch a star for a slight dip in its brightness. This occurs when an orbiting planet passes in front of the star and blocks part of its light. At most, a tenth of all planetary systems are oriented so that these mini-eclipses (日食，月食) — called transits (凌日) — are visible from Earth. So, astronomers have to monitor a lot of stars to capture just a few transits.

The dream of astronomers is to discover a rocky planet roughly the size of Earth orbiting in a habitable zone, one that is neither too hot nor too cold to support life. If they succeed, they will have found what biologists believe could be a promising residence for life.

The best places to look may be dwarf stars. Smaller than the sun, dwarf stars are plentiful; seven of the ten stars nearest to Earth are dwarf stars. They also provide a steady supply of sunlight to any life-bearing planets within their habitable zone. Additionally, dwarf stars are dim, so the habitable zone lies closer in. If the planet is closer to the star, it’s easier for astronomers to detect a transit observation. A close-in planet also has a stronger pull on its star. That makes it easier to detect with the Doppler method.