We may not be aware of it, but ordinary family homes in the U.S. and the rest of the world are not energy-efficient.

    Most of their energy goes to heating and cooling, and a lot of it is wasted, as warm air and cool air escape through fireplace chimneys and thin or poorly fitting windows and doors. A passive house loses almost none."Imagine a thermos(保温瓶),"said housing developer Brendan O'Neill."You have insulation(隔绝) everywhere, and it's basically completely sealed. And so the idea is to build a house like a thermos. So the windows are sealed. There's insulation completely surrounding the building. We make it as sealed as possible."

    A 147-square-meter passive house, presented by O'Neill Development Corp. as a demonstration unit just outside Washington, was brought to the site in two boxes. "Once it's set and put together, it takes about four weeks to complete the outside construction, to put down carpets," O'Neill said. "If everything is set in place, you put a house like this together in about four months.”The total cost of building it was $325,000, or about 17 percent more than constructing an ordinary house. But its utility(公用事业) bill is only around $20 monthly, or one-tenth the amount for the average house of the same size.

    While passive houses have been around for a long time, the idea has never taken root in the U.S. There was no driving force to push it.

    However, David Peabody, an architect who designs passive houses said, "I think climate change is now becoming a larger issue. And I think building standards are catching on to that. So people are becoming more aware of energy."Peabody said the cost of building passive houses could come down."What really makes sense for truly affordable housing," he said, "is to build multi-storey buildings."

    Johnny Smith was a good math student at a high school. He loved his computer. He came home early every day, then he worked with it till midnight. But Johnny was not a good English student, not good at all. He got an F in his English class. One day after school Johnny joined his computer to the computer in his high school office. The school office computer had the grades of all the students: the math grades, the science grades, the grades in arts and music, and the grades in English. He found his English grade. An F! Johnny changed his English grade from an F to A. Johnny' parents looked at his report card. They were very happy.

    "An A in English!" said Johnny's Dad. "You're a very clever boy, Johnny."

    Johnny is a hacker (黑客). Hackers know how to take informationfrom other computers and put new information in. Using a modem, they join their computers to other computers secretly. School headmasters and teachers are worried about hackers. So are the police, for some people even take money from bank computer accountand put it into their own ones. And they never have to leave home to do it! They are called hackers.

    How fit are your teeth? Are you lazy about brushing them? Never fear: An inventor is on the case. An electric toothbrush senses how long and how well you brush and it lets you track your performance on your phone.

    The Kolibree toothbrush was exhibited at the International Consumer Electronics Show in Las Vegas this week. It senses how it is moved and can send the information to an Android phone or iPhone via a Bluetooth wireless connection.

    The toothbrush will be able to teach you to brush right (don't forget the insides of the teeth!) and make sure you're brushing long enough. “It's kind of like having a dentist actually watch your brushing on a day-to-day basis,” says Thomas Serval, the French inventor.

    The toothbrush will also be able to talk to other applications on your phone, so developers could, for example, create a game controlled by your toothbrush. You could score points for beating monsters among your teeth. “We try to make it smart and fun,” Serval says.

    Serval says he was inspired by his experience as a father. He would come home from work and ask his kids if they had brushed their teeth. They said “yes,” but Serval would find their toothbrush heads dry. He decided he needed a brush that really told him how well his children brushed.

    The company says the Kolibree will go on sale this summer, from $99 to $199, and the U.S. is the first target market.

    One day a poor man was begging with an old wallet in his hand. As he felt sad at his own bad luck, he kept wondering why some wealthy people were never satisfied and were always wanting more.

    "Here," said he, "is the master of this house—I know him well. He is a wealthy businessman. He should have turned over his business to others, and then he could have spent the rest of his life happily, but he didn't. Instead, he sent his ships to sea to trade with foreign lands. However, there were great storms on the water, so his ships were destroyed and his treasure disappeared in the sea. As for me, if I had only enough to eat and to buy clothing, I would not want anything more."

    Just at that moment, Fortune came down the street. She saw the poor man and stopped. She said to him, "Listen! I want to help you. Hold your wallet, and I will pour this gold into it, but only on this condition: all that falls into the wallet shall be pure gold, but every piece that falls upon the ground shall become dust. Do you understand?"

    "Oh, yes," said the poor man.

    "Then be careful," said Fortune. "Your wallet is old, so do not load it too heavily."

    The beggar was so glad that he quickly opened his wallet, and a stream of yellow dollars poured into it. The wallet grew heavy.

    "Is that enough?" asked Fortune.

    "Not yet."

    "Isn't the wallet cracking (裂开)?"

    "Never fear."

    The beggar's hands began to tremble. Ah, if the gold would only pour forever!

    "You are the richest man in the world now!"

    "Just a little more, add just a handful or two."

    Another piece was added, and the wallet cracked. The treasure fell upon the ground and turned to dust. The beggar had nothing now but his empty wallet. He was as poor as before.

Everyone gets anxious when the world takes an uncertain turn. And often, we treat that anxiety with a little panic buying.

A study published last year in the Journal of Consumer Research found that people buy things in troubled times as a means of keeping control over their lives. The researchers noted that utility items — specifically, cleaning products — tend to move most quickly from store shelves. The hoarding (囤积) of toilet paper, as perhaps the most fundamental cleaning product, may represent our most fundamental fears. An invisible enemy moves slowly and quietly towards us. We need to hold on to something in uncertain times. Maybe a hoard of toilet paper brings promises.

The thing is, it's not actually going anywhere. For all the sharp words and even sharper elbows thrown around by the crazy toilet paper shoppers, they seem to be missing one essential fact: There is no toilet paper shortage.

As The New York Times points out, shop owners that see their shelves emptied often fill up the shelves again in a day, often in just a few hours.

"You are not using more of it. You are just filling up your closet with it," Jeff Anderson, president of paper product manufacturer Precision Paper Converters, tells the Times.

The thing is, the toilet paper-obsessed shoppers have been infected with something many times more contagious (感染性的) than any coronavirus: fear.

"People are social creatures. We look to each other for cues for what is safe and what is dangerous," Steven Taylor, a clinical psychologist at the University of British Columbia, tells Fox News. "And when you see someone in the store panic-buying, that can cause a fear contagion effect. People become anxious ahead of the actual infection. They haven't thought about the bigger picture, like what are the consequences of hoarding toilet paper."