The word“day” has two meanings. When we talk about the number of days in a year,  we are using “day” to mean 24 hours. But when we talk about day and night,  we are using“day” to mean the time between sunrise and sunset. Since the earth looks like a ball,  the sun can shine on only half of it at a time. Always one half of the earth is having day and the other half night. A place is moved from day into night and from night into day over and over by the spinning（旋转）of the earth. At the equator（赤道）day and night are sometimes the same length（长度）. They are each twelve hours long. The sun rises at 6 o'clock in the morning and sets at 6 o'clock in the evening. For six months the North Pole is tilted（倾斜）toward the sun. In those months the Northern Hemisphere（半球）gets more hours of sunlight than the Southern Hemisphere. Days are longer than nights. South of the equator nights are longer than days. For the other six months the North Pole is tilted away from the sun. Then the Southern Hemisphere gets more sunlight. Days are longer than nights. North of the equator nights are longer than days. Winter is the season of long nights. Summer is the season of long days.

    Valentine's Day（情人节） is on February 14th every year. On this day, people send valentines to their loved ones. Valentine's Day is a special time to tell how much you care about（在乎） a person.

    Many people send candy in hearted shaped（心形的） boxes to people they love. Flowers are also presents that people send on Valentine's Day. Valentine cards with words are often used（被使用） by many people.

    Can you guess who gets the greatest number of Valentine cards in the USA each year? Is It mother or father, sister or brother? Is it uncle or aunt? Is it the special friend? No, it isn't!

    Mothers get a lot of cards, but school teachers get the most each year. Do you know who sends the most? Children do. Children send five times（倍） as many on February 14th as adults do.

    In summer, it's common on the street to see many Chinese women holding parasols¹ to protect themselves from the sun.  But when Amy, an exchange student in Beijing from the US, first saw this, she found it strange, even impossible to understand.  She wrote on her blog, "Unlike Chinese women, American women like to put on their tank tops and sunglasses during summer. If you walk around an American college campus², you will probably see girls out on the grassy fields reading, but they really hope to get a head start on their summer tan³."

    This may be caused by the different standards of beauty between the US and China. Many Americans don't want white skin. They would rather be tanned³. Amy also wrote, "Having darker skin is so popular that many women and men will pay for fake⁴ tans so that they can keep their sun-kissed appearance during the winter months, too."

    Why do they like tanned skin? Michelle Louis reported in her research, "The process of tanning can help make people's skin smooth and hide marks." She further explained, "Tans make people's skin appear healthier and make them appear thinner than when they have pale skin."

    Perhaps there is no real ideal standard of beauty. In different cultures and at different times of history, the standards change. On Amy's blog, she also gave two examples: Some women carried parasols around trying to keep their white skin in the US 150 years ago; During the Tang Dynasty in China, heavy women were thought attractive. But now, Chinese women prefer to be slim.

    In a word, different standards of beauty should be respected. People may grow up with only one idea of what beauty is, but it doesn't mean that it's necessarily the correct or the best idea.

New words:

①parasol n. umbrella used to protect people from the sun 阳伞

②campus n. grounds of school, college or university校园

③tan n. the brown colour of sun-kissed skin 晒成的棕褐

④become brown by the sun 晒成棕褐色，晒黑

⑤fake adj. not real 假的