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 doctor 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(应用) on your phone, so developers could, for example, create a game controlled by your toothbrush. You could score points for beating monsters(怪物) among your teeth. “We try to make it smart but also 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, for $99 to $199, depending on features. The U.S. is the first target market.

    Serval says that one day, it'll be possible to replace the brush on the handle with a brushing unit that also has a camera. The camera can even examine holes in your teeth while you brush.

    Can technology improve your trip? Meet Judy Williams. When she and her husband recently checked into Blu Hotel in Zurich, a clerk asked them to sign the dotted line on a room rate hundreds of dollars higher than their online offer.

    “It was not a cheap stay,” says Williams, a lawyer from Billings, Mont. But it became more of one after her husband fired up the Booking.com app he'd used to book their room on his smart phone. “As soon as we showed him the cost, he honored it,” Williams says.

    Technology may create challenges for travelers but it can also solve them. It's more than making sure of a hotel cost. The latest Booking.com can help users select hotels by location, make a secure booking and view the confirmed (已确认的) cost so they never need to re-discuss their hotel price.

    Another pain point for travelers is traffic that eats away precious vacation time. There's a new app called Commute which is aimed at users who have to make the same trip every day. But if you're headed to Los Angeles or Honolulu, where visitors can easily get stuck in hours of heavy traffic, Commute can help.         

    Just input basic information about your destination and expected leaving time, and the app will start sending you traffic information 15 minutes before you leave. Testing Commute proved to be a challenge for me, because my home address is about 900 miles from my place of work. But if you have only a short distance to travel through a heavily populated area, you can use Commute to avoid traffic jams.

    Another source of travel-related problems is money. That's particularly true when you're dealing with a foreign currency. The latest Travel Money Tracker helps travelers prevent currency mix-ups. It immediately changes a country's native currency to yours, so you know exactly how much that Espresso (浓咖啡) in Milan costs in dollars. It can also warn you when you're overspending, which can sometimes be a problem when you're on vacation. The only catch, of course, is that you have to remember to record all your purchases.

    Taken together, these apps solve some of the most common travel problems. But not all of them. Some things, no smart phone can fix, which means I get to keep my job – for now at least.

    The eyes are the windows of the soul. Having a pair of bright, clear eyes is very important, so we should protect our eyes throughout our lives.

    {#blank#}1{#/blank#} Don't read while lying down or walking. Relax after every hour of reading.

    Keep a distance from the TV set when you watch TV and give your eyes a rest every 30 minutes.

    Don't stare at the sun or try to read in the darkness.{#blank#}2{#/blank#} This can damage your eyes easily.

    Get your eyes checked often. Not many people have this habit, but it is necessary. If you feel that there is something wrong with your eyes, get them checked quickly.{#blank#}3{#/blank#}

    {#blank#}4{#/blank#} You can close your eyes for a few seconds or look into the distance for one or two minutes. A small break will relax your eyes and help to stop you from getting eye problems.

    Be careful when you choose your glasses.{#blank#}5{#/blank#}. Make sure your glasses are right for you . If they don't feel right, get your glasses changed.

A. Develop good reading habits.

B. Rest your eyes whenever you can.

C. Make sure you get enough sleep every night.

D. Glasses that aren't suitable for you could bring you trouble.

E. Even if you're wearing sunglasses, never look directly at the sun.

F. Eye problem can be found and treated early with regular checks.

G. Drink green tea every day as a way to protect your eyes against eye problems.

    Have you ever noticed what happens to an idea once you express it? Just talking about it or writing it down causes you to make it clear in your own mind. How can you use this to increase your brain power? Start writing.

    By putting thoughts into words, you are telling yourself the logic (逻辑) behind what you think, feel, or only partly understand. Often, explaining a thought is the process of understanding. In other words, you increase your brain power by exercising your “explain power.”

    Try this experiment. Explain how you'll increase your brain power, even if you have no idea right now. Just start with anything, and create an explanation. For example, start with “I'll learn chess,” or “I'll read an article on the mind every week.” Explain how that will help. You'll be surprised how often this becomes a workable plan, and if you actually do this, you'll have a better understanding of your brain from now.

    Another benefit of writing is that it helps you remember. Many, if not most, highly productive people are always taking notes. You can try keeping it all in your head, but if you keep a journal of your ideas the next time you're working on a big project, you'll probably have more success.

    Want to understand a topic? Write a book about it. That's an extreme example, but if you are learning something new, write a letter to a friend about it, and you will understand it better. Want to invent something? Write an explanation of the problem, why you want to solve it, and why it is worth solving, and you're half-way there.

    Writers don't always write because they clearly understand something beforehand. Often, they write about something because they want to understand it. You can do the same. Writing will help bring you to an understanding. Give it a try.

Memorial Day is a time that many associate with a slower pace affording, maybe, a little more free time to read. We asked some of our regular book reviewers what titles they are most looking forward to reading this summer. Here's what they said.