2 . Who doesn’t dream of a bright, beautiful, pearly-white smile? It’s something most of us long for — after all, great teeth are a sign of good health, fortune, and youth.     1    . It's people's lifestyles that are contributing to poor tooth health. Here we have listed the worst habits for your teeth.

Avoiding your dentist (牙医)

How often do you go to the dentist?     2     According to reports, around 33 percent of the population in Britain do not visit their dentists as often as they should. This is unfortunate as seeing a dentist regularly is often your first line of defence against more severe dental diseases.

    3    

For some reason, most people get into the habit of moving their brushes back and forth over their teeth. Now, you may think that this is getting rid of all the germs (细菌) but there are actually better methods you should employ. Instead of back and forth, you should be using short, circular movements to brush your teeth.

Not flossing (用牙线清洁牙齿) regularly

    4     However, this simply isn’t the case. Though regular brushing gets rid of the germs on the surface of your teeth, it often has little impact on the food stuck between your teeth, which is all germs need. This is why it is important to floss at least once a day.

Sipping sugary drinks all day

By drinking sugary drinks throughout the day, your teeth are being exposed to sugar for greater amounts of time which can lead to higher levels of tooth decay (蛀蚀) and other oral health issues. So, what should you do? Well, to start with, try to reduce your intake of sugary drinks as much as possible.     5    

3 . Your dentist has probably been telling you to floss for years.     1     36% of Americans would rather do something unpleasant, like clean the toilet, than put string between their teeth.

That’s why many cheered at a news report that flossing might not be necessary. The Associated Press reviewed 25 studies and concluded that flossing didn’t have proven health benefits. Should you throw away your floss? Not so fast.    2    

One review of 12 studies found that people who brushed and flossed regularly were less likely to have bleeding gums.     3     Gum disease, left untreated, can lead to shrinking gums and tooth loss. It is also linked to heart disease, and many other health conditions. “Your mouth is a mirror for the rest of your body,’ experts say.

    4     Some think more bacteria left in your mouth end up in your bloodstream, where they may contribute to inflammation in other areas, like your heart. What experts do know is that people who don’t have gum disease are less likely to have health problems like heart disease.

In fact, many dentists say the reason they recommend flossing isn’t because of research.     5     “In my practice, it’s clear that people who floss daily have healthier gums and keep their teeth longer,” a dentist says. It takes less than a minute, and there’s literally no downside to doing it. But if you skip it, sooner or later you—and your dentist—will notice a difference.

Being nearsighted is more common     1     it once was. It occurs when eyeballs are longer than normal,     2     (change) the angle (角度) at which light enters the eye and therefore the ability to focus on distant objects.

More and more researchers indicate that     3     lack of direct sunlight may reshape the human eye and damage vision. Those     4     were exposed to the sun frequently, particularly between the ages 14 and 19, were about 25 percent     5     (little) likely to have developed nearsightedness by middle age.

So, how much sunlight should you get?

Scientist Kathryn Rose recommends at least 10 to 14 hours per week in addition to any time     6     (spend) outdoors while at school. This is the level at which her     7     (study) have found a preventative effect. Lower amounts of sunlight, like 3 to 6 hours,     8     (show) no effect on vision.

Ten to 14 hours a week may seem like a lot to you, but you need the sun for more than just your vision. Sunlight has a direct     9     (connect) to vitamin D levels, mood, and even weight.

And these benefits aren't limited to children. Exposure     10     sunlight up to the age of 30 also confers (授予) a protective benefit.

5 . Ways to protect eyes from screens

Too much screen time may cause serious eye strain (眼疲劳) and even a sharp decline of eyesight. That's a big problem a lot of people are faced with nowadays, especially those who work on a computer. The following tips may be helpful.

Get regular eye tests

Experts recommend having a comprehensive eye exam every year to detect (探测) problems before they develop. During this test, you should tell the doctor how often you use your phone and your computer.     1     Tell your doctor about it, and your eyes can be tested more accurately at that distance.

Give your eyes space

    2     Studies on computer-related eye strain suggest that screens should be no closer than 40 cm from your face. If this makes it hard for you to read, consider increasing the size of the text rather than moving the screen closer.

Take breaks

This may not always be practical if you're quite busy, but it's important not to stare directly at a screen for too long.     3     While surveys have shown that many office workers take no more than half an hour a day away from their computer, it's recommended that you take a 15-minute break after every two hours spent at your screen.

    4    

Staring at a screen continuously for hours on end may make it difficult for you to focus. To avoid this, many eye experts recommend the “20-20-20 rule” — looking away from your phone/computer screen every 20 minutes and focusing on an object at least 20 feet away for at least 20 seconds. The science behind his trick is that looking at objects at a distance relaxes the focusing muscle in the eye.     5    

Skin is not only large, but it is important. One of its jobs is to protect us,     1     keeps bad things out. But sometimes it fails.     2    (extreme) small bugs, called mites, can get under our skin. And when they do, they cause itching and great discomfort. So, to get under someone’s skin means to annoy them or to bug them. That’s just one definition of the     3    (express) “to get under someone’s skin.” It can also mean that someone is very     4    (attract) to you. You can’t stop thinking about them. You might even be obsessing about them.

There are many ways     5    (describe) people using the word “skin”. If someone is thick-skinned they are not easily hurt emotionally. You can criticize them or be unkind to them and it simply rolls off their back. Thin-skinned people,     6    , are easily hurt by criticism, even if it is not too severe. You have to be careful about     7     you say to thin-skinned people so as not to hurt their feelings.

If someone is suddenly very     8    (scare), you can say they nearly jumped out of their skin! For example, one day I saw my friend Sierra     9    (wait) at a bus stop. She was wearing headphones and did not hear me come up behind her. So, when I     10    (touch) her shoulder, she nearly jumped out of her skin!