Even before my father left us, my mother had to go back to work to support our family. Once I came out of the kitchen, complaining, “Mum, I can't peel(削皮) potatoes. I have only one hand.”

    Mum never looked up from sewing. “You get yourself into that kitchen and peel those potatoes,” she told me. “And don't ever use that as an excuse for anything again!”

    In the second grade, our teacher lined up my class on the playground and had each of us race across the monkey bars, swinging from one high steel rod(杆) to the next. When it was my turn, I shook my head. Some kids behind me laughed, and I went home crying.

    That night I told Mum about it. She hugged me, and I saw her “we'll see about that” look. The next afternoon, she took me back to school. At the deserted playground, mum looked carefully at the bars.

    “Now, pull up with your right arm,” she advised. She stood by as I struggled to lift myself with my right hand until I could hook the bar with my other elbow. Day after day we practiced, and she praised me for every rung(横杠) I reached.

    I'll never forget the next time, crossing the rungs; I looked down at the kids who were standing with their mouths open.

    One night, after a dance at my new junior high, I lay in bed sobbing. I could hear Mum came into my room. “Mum,” I said, weeping, “none of the boys would dance with me.”

    For a long time, I didn't hear anything. Then she said, “Oh, honey, someday you'll be beating those boys off with a bat.” Her voice was faint and cracking. I peeked(偷看) out from my covers to see tears running down her cheeks. Then I knew how much she suffered on my behalf. She had never let me see her tears.

    Dutch officials toasted on Tuesday the opening of what is being called the world's first 3D-printed concrete bridge, which is meant to be used by cyclists. There was applause as officials wearing hard hats and workmen's jackets rode over the bridge on their bikes at the opening ceremony in the southeastern town of Gemert.

    “The bridge is not very big, but it was rolled out by a printer which makes it unique,” Theo Salet, from the Eindhoven University of Technology, told Dutch broadcaster NOS. Work on printing the bridge, which has some 800 layers, took about three months after starting in June and it is made of pre-stressed concrete, according to the university. “One of the advantages of printing a bridge is that much less concrete is needed than in the conventional technique in which a mould (泥浆) is filled,” it said on its website, adding “a printer deposits the concrete only where it is needed.”

    The eight-metre (26-foot) bridge crosses a water-filled channel to connect two roads, and it was tested for safety to bear loads of up to two metric tons in cooperation with the BAM Infra Construction company. Although designed for bikes, it could take up to 40 trucks, the designers said “We are looking to the future,” said the head of BAM, Marinus Schimmel. “3D printing meant fewer rare resources were needed and there was significantly less waste,” he added.

    The Netherlands is among countries, with the United States and China, taking a lead in the cutting-edge technology of 3D printing, using computers and robotics to construct objects and structures from scratch without using much traditional manpower. Last year a Dutch architect unveiled (提示) a unique 3D printer with which he hopes to construct an “endless loop” building. And a Dutch start-up called MX3D has begun printing a stainless-steel bridge, of which a third is already completed. The aim is to finish printing by March and lay the bridge over an Amsterdam canal in the future.

    Are you a social media addict? Are you always checking your smart phone to see how many "likes" you've received for your latest post? Maybe you feel comforted by the sound that someone has sent you a message?

    Don't worry, you're not alone. We check our phones an average of 150 times a day, and around 30% of the total time spent online is devoted to social media. Some experts now fear this habit could be damaging our mental health.

    This is something particularly bothering young adults, according to a study from the University of Pittsburgh. It found the more they used social media, the more likely they were to be depressed. In tests, those people who checked social media frequently were 2.7 times more likely to be depressed compared to those who spent most of their time generally surfing the Internet, who had just 1.7 times the risk.

    Some of us certainly feel sad when we're ignored on social media sites, or when we see someone else having a better time than us. But depression is a more serious condition and clinical psychologist, Abigael San, recently told the BBC that ,"It's a real issue, and it's been getting significantly worse over the last 5﹣6 years. You can get so hooked that it takes you away from your real relationships. "However, Abigael does admit that social media is more likely to worsen pre﹣existing issues than directly cause them.

    Other research by the University of Glasgow found that teenagers are affected by the 24﹣hour demands of their social media accounts. It found that those with higher levels of emotional investment in social media, and who use it at night, were more likely to feel depressed and anxious.

    Despite these warning signs, why do some of us continue to keep clicking? Well, I suppose we all want to be liked and we don't want to miss out on a conversation that's taking place online. But we need to know when to switch off our virtual online world and connect with the real world instead.

    When young, I loved going on trail(小路) runs. It was my favorite way to escape stress. So, when I was back in my hometown after a tough first year of my Ph. D. program, I thought a trail run was just what I needed. But instead of helping me relax, the run did just the opposite.

    After I moved to the city for college, where my runs were on flat concrete paths instead of winding dirt trails, I used a GPS watch. When I went on trail runs again in the country, it constantly reminded me of the fact that I wasn't keeping up with my usual pace. I turned my watch off, thinking that would allow me to enjoy my surroundings and find the peace I expected, but I worried I was underperforming. "Why can't I let go and just enjoy myself?" I wondered. But after some introspection(反省), I realized why I was struggling­both on trail runs and in graduate school.

    Going into my Ph. D. , I had thought that my solid undergraduate track record would set me up for instant success. To my surprise, I was wrong. I lacked confidence in my research abilities which I thought stopped me performing well and I constantly felt my progress was too slow. Other students'self-confidence and their excellent results made me feel insecure. Finally, one day I broke down in tears in my adviser's office.

    Then came my visit home: I was having trouble because I hadn't properly adjusted my expectations to the differences between an urban run and a trail run.

    A Ph. D. is like a trail run: Sometimes you can run fast. Sometimes you might find yourself climbing up a steep, winding trail at a snail's pace. And that's OK. Barriers are unavoidable, and success looks and feels different on a challenging trail than it does on a smooth, flat path. Sometimes it's best to take a deep breath and do your best to meet the challenge.

China Experience Tours

    China Experience Trip

    Beijing →Shanghai →Xi'an (8days)

    Price: Adult $1,517 p/p Under 17 $1,230

    Imagine you are a king or queen when entering the great Forbidden City

    Have a hike on the world famous Great Wall

    Discover the Terracotta Warriors (兵马俑)

    Admire Shanghai where east meets west and walk around some local markets

    Glories of China

    Beijing →Xi'an →Guilin →Yangshuo →Shanghai (11days)

    Price: Adult $2,219 p/p. Under 17 $1,650

    Discover more of China's extraordinary history from Beijing and Xi'an

    Visit the easy part of the Great Wall at Mutianyu

    Cycle near Yangshuo and admire the beautiful rural scenery

    Discover Shanghai lifestyles ancient and modern

    China Impression Experience

    Beijing →Xi'an →Yangtze River →Shanghai (11 days)

    Price: Adult $2, 329 p/p. Under 17 $1,810

    Explore both the ancient cultures and modern features, and relax on the yangtze river Cruise (乘船游览) to see the various ideas of China. Your guides will show you around not only the most classic spots, like the Forbidden City, the Great Wall, the Terracotta Army, and the Three Gorges but also take you for a local experience by visiting lovely giant pandas and local markets.

    Cultural and Natural Wonders of China

    Beijing →Xi'an → Zhangjiajie →Shanghai (11days)

    Price: Adult $2,159 p/p. Under 17 $1,360

    Wind your way from Beijing to Shanghai in style and discover. Climb up the Great Wall, walk around the Forbidden City while listening to the stories of kings, and see the Great "Avatar Mountain" in Zhangjiajie.

Mr. and Mrs. Smith have two children, Kevin and Jenny. The whole family are all busy, so they often leave notes to each other. Here are these four notes of today.