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Natural Ways to Whiten Your Teeth at Home
Baking soda tops the list as the best-known natural ingredient for tooth whitening. You probably have a box in your kitchen pantry. It’s inexpensive, safe for many purposes, and can be found anywhere. And it can play a starring role in your dental routine.
Baking soda is naturally a mild abrasive, making it perfectly suited for gently scrubbing away plaque from the surface of teeth. It’s also an effective tool in the fight against surface tooth staining.
A review of clinical studies examining the stain-removing effectiveness of baking soda published in the November 2017 edition of the Journal of the American Dental Association, consistently found that “baking soda-based dentifrices are effective and safe for tooth stain removal and consequently whitening”—and sometimes even more effective than their non-baking soda-containing counterparts.
Baking soda also has antibacterial and antimicrobial properties, which can help with the prevention of oral infections. At 10 cents per ounce or less, it’s the most affordable option available for at-home whitening.
想一想：
1. 根據本文，關於美白牙齒，下列敘述哪一項錯誤？（1）小蘇打粉有殺菌功效。（2）牙膏含小蘇打成分，能有效美白牙齒。（3）小蘇打粉無法去除牙菌斑。（4）小蘇打粉是美白牙齒最天然的工具。
2. 根據本文，為什麼小蘇打粉可以預防口腔感染？
3. 您也有一口潔白晶亮的牙齒嗎？請問您都怎麼保養牙齒，有沒有其他撇步？
解答：
1. （3）
2. Baking soda has antibacterial and antimicrobial properties.（小蘇打粉可抗菌和抗微生物。）
（文章來源：英文大紀元時報）
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文章二：
How Much Exercise Do You Really Need?
How Much Exercise Do You Really Need?（123RF）So how much should we really be moving? The updated “Physical Activity Guidelines for Americans” offers recommendations. Preschool-aged children (below 5 years old) should be given plenty of opportunity to be physically active throughout the day (something that happens naturally when screens are turned off), while children and adolescents aged 6 to 17 need at least 60 minutes of moderate to vigorous physical activity per day.
Adults should do between 150 and 300 minutes of moderate activity, or 75 to 150 minutes of vigorous activity, each day, as well as some muscle-strengthening activities at least twice per week. Older adults should follow these guidelines and also include some balance training in their fitness routine. Moderate activity can be defined as anything that raises the heart rate and gets you breathing harder, but not so hard that you can’t carry on a conversation.
Fitness guidelines provide a useful benchmark to give us some idea of what a healthy fitness level is for the majority of people. But individual circumstances do differ. Those suffering from chronic conditions that make vigorous exercise difficult or impossible will need to modify their fitness routine according to their abilities.
想一想：
1. 根據本文，下列何者有誤？（1）健康的成人每天應該至少劇烈運動150分鐘。（2）3歲幼兒每天應有大量的身體活動機會。（3）青少年每日至少要1小時，強度中等至劇烈的運動。（4）心跳加快、呼吸微喘屬於強度中等的運動。
2. 根據本文，何謂「強度中等」的運動？
3. 您每天有運動嗎？喜歡什麼樣的運動？有什麼動機促使你運動？
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解答：
1.（1）
2. 解答：Moderate activity can be defined as anything that raises the heart rate and gets you breathing harder, but not so hard that you can’t carry on a conversation.（強度中等的運動可定義為：讓你心率提高、呼吸短促，但又不至於無法說話。）
（文章來源：英文大紀元時報）◇
