PM stands for particulate (微粒的)matter: the term for a mixture of solid particles(粒子) and liquid droplets in the air. Some particles are large or dark enough to be seen by our eyes. Others are so small that they can only  (discover) with a microscope.

These particles come in many sizes and  (shape) and can be made up of many different chemicals. Some come directly from a source, such as fields or fires. Most particles form the atmosphere as a result of complex reactions of chemicals,  are pollutants from power plants, industries and automobiles.

Particulate matter (contain) microscopic particles that are so small that they can be breathed in and make one  (serious) ill. Some particles less than 10 micrometers in diameter can get deep into your lungs  some may even get into your bloodstream. Of these, particles less than 2.5 micrometers in diameter, also known as PM2.5, create the  (great) risk to health.

Fortunately, every day the Air Quality Index (AQI) tells you how clean or  (pollute) your outdoor air is, along with associated health effects that may be of concern. The AQI translates air quality data into numbers and colors that help you understand when  (take) action to protect your health.

    A famous teacher was speaking to the students at our school. He began his lesson by holding up a ￡100 bill. Then he said to the three hundred students, "Who would like to have this ￡100 bill?" The students began to put up their hands at once.

    Then he said, "I am going to give this bill to one of you, but first, let me do this." He then made this bill into a ball. Then he said, "Who wants it?" Hands went into the air.

    "Well," he said, "What if I do this?" and he dropped it on the floor and stepped on it. He picked up the dirty, crumpled bill and said, "Who still wants it?" Hands went back into the air.

    "My friends," he said, "You've learned a valuable lesson today. No matter what I did to the money, you still wanted it because it didn't go down in value. It was still worth ￡100.”

     “Many times in our lives, we're dropped, crumpled, and stepped on by the chances we take and the things that happen to us. We feel as if we are worth nothing. But remember, no matter what has happened to you, you will never lose your value: you are always valuable to those who love you. Your value doesn't come from what you drop or whom you know, but WHO YOU ARE.”

    You are special and valuable. Don't ever forget it!

    The TED speaker series features “ideas worth spreading”. With over 1,400 to choose from, we've selected a few that are perfect for students.

    Larry Smith: Why you will fail to have a great career

    We humans may have an unfavorable habit of making excuses for ourselves of or being too confident about ourselves. Accordingly, Larry Smith, a professor of economics at the University of Waterloo in Canada, tells us why most of us will fail to have a great career. Luckily, as he puts it, there is a way out-follow your heart, as long as it is good for your career.

    Andy Puddicombe: All it takes is 10 mindful minutes

Between dance team, volunteering and –oh, right—lectures, your life's crazy factor（因素）is about to go way up. In this entertaining and informative talk, Mindfulness, expert Andy Puddicombe teaches us how to be “more healthy, more mindful and less distracted” by taking just 10 minutes out of the day to be “more present”.

    Shane Koyczan: To this day…for the bullied（欺凌）and beautiful

    This talk is sure to stay with you. Shane Koyczan's “To This Day” is an affecting spoken-word poem about bullying and being different that gained over 10 million views on YouTube. In this talk, Koyczan gives a live reading of the poem, along with some stories about his background.

    Susan Cain: The power of introverts（性格内向者）

    Does a cup of tea and a good book sound like a perfect Friday night? In this personal talk, Susan Cain argues that introverts have talents and abilities. Our culture may value being outgoing, but the world needs all kinds.

    Rugby looks like a (mix) of soccer and American football. Legend says rugby was invented in 1823 at a school in the town of Rugby, England. A student was playing in a soccer match, but he got (bore) with just kicking the ball, so he picked it up and ran with it. Before long, this new way of playing soccer became popular at the school. When the school's students finished their studies, they moved to other parts of Britain, (take) the new game, they called rugby, with them. Before long, they established rugby (club) throughout Britain and in British colonies around the world.

    By the 1870s, there were many rugby clubs in Britain and elsewhere, but they weren't all playing rugby the same way. To solve this problem, representatives from twenty-two teams met agreed on official rugby regulations. They also founded association (协会) of rugby teams, called the Rugby Football Union (RFU).

    Today, Rugby Union World Cup tournaments (hold) every four years. Thousands of fans travel (attend) the matches and cheer on their favorite teams. Believe it or not, not one team who's won the Rugby World Cup has (success) won the next World Cup! But players and fans don't mind. They just enjoy the game.

增加：在缺词处加一个漏词符号（∧），并在其下面写出该加的词。

删除：把多余的词用斜线（\）划掉。

修改：在错的词下划一横线，并在该词下面写出修改后的词。

注意：

1). 每处错误及其修改均仅限一词；

2). 只允许修改10处，多者（从第11处起）不计分。

    Last month while I was walking in the street, the foreigner came towards me. She seemed to be losing. She asked me if I could help him. I said yes, but when she started talking, I couldn't understand that she said. I could only say ＂I don't know＂, and then slowly walk away. Though I have studied English for six years, but I still can't understand English good enough. I know I'm not interested in English and I've also been very lazy to study it. Now I know the importances of learning English. I've decided change my attitude towards English and work hard on it.

Cala didn't like us. Any of us. We didn't do anything to offend her and she didn't know us but that didn't matter; she still didn't like us.

As new teachers in the Emirati school, we Westerners greeted her every day. She ignored us. She came into our rooms and bypassed us as she shook hands with all the non-Westerners. When- ever we saw her, she avoided eye contact with us. Eventually, we stopped trying to befriend her.

I wouldn't say her nationality but her friends had been fired from the school. We had been employed in their places and that was enough for her to have nothing to do with us.

Well after 16 months in the school we had a secret friend gifting. To my surprise, I drew her name from the glass jar and that meant she was my secret friend. My role was to buy her a gift and say some- thing about her when we publicly acknowledged who our secret friend was.

I decided to gift her a coloured bangle（手镯）. I added a postcard and wrote "Love and Blessings, Rose Marie. "

Then came the day. We all gathered in the meeting room. When you gave your gift, you said a few kind words about your secret friend and passed the gift to her. What could I say? Everyone knew she didn't like the Westerners. She taught music in the school, so I said "My secret friend is someone who brings music to our ears every day. "She came forward with a huge warm smile. She hugged me and kissed me on both cheeks and accepted my gift.

Since then, she smiles often. We hug and shake hands when we meet. I have seen her wear my gift several times and I am so pleased.

    “Shine in the dark” dolphins may seem like something straight out of a science fiction movie. However, that is precisely what Newport Coastal Adventures' Captain Ryan Lawler and professional videographer Patrick Coyne witnessed, when they set out to explore the spectacular blue tides that have been lighting up the waters off Southern California's coast since mid-April.

    The partner scanned the ocean for hours and was returning to shore when they spotted the “electric” dolphins swimming through the bloom of shining plankton(浮游生物). The videographer, who had seen the phenomenon only once before in a Netflix show, says catching the scenes proved to be a lot harder than he had expected. “For starters, the shining plankton has sweet spots to where it shows up and then fades away, so while on the water, it's impossible to just find it,” Coyne says. “Also, conditions have to be absolutely perfect for the shining plankton to show and for animals to swim through it so we can film it.”

    Though witnessing shining sea life is rare, the electrifying blue ocean scenery is a fairly common sight around Southern California between February and September. The phenomenon can be attributed to the presence of millions of plankton, which tend to gather and reproduce in large quantities in the warm coastal waters during this time.

    Though a majority of California's red tides are caused by plankton species that do not produce deadly poison, some algal blooms(藻花)can be dangerous for sea animals, especially when they stay for long periods of time. In 2018, an almost year-long “red tide” along Florida's Gulf coast caused by the excessive growth of microalgae Karenia Brevis, killed hundreds of fish and other sea animals.

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    Helping and supporting others may be key to living a longer and healthier life, according to a new research from the University of Bagel in Switzerland. The findings published in the journal Evolution and Human Behavior, show that grandparents who care for their grandchildren enjoy longer lifespans. So do old people who care for others within their social networks.

    Using data from the Berlin Aging Study, the researchers analyzed the longevity(寿命) and caregiving habits of more than 500 old people between the ages of 70 and 103. The study compared grandparents who acted as occasional caregivers with those who did not. It also compared these grandparents with old adults who did not have grandchildren but cared for people within their social networks.

    Those grandparents who did not play the role of attending to grandchildren were more likely to have died within just five years of the testing period. While those old adults who provided, support to their family lived for an extra seven years on average and those provided support to their social networks lived for an extra four years on average.

    Although the new study only focused on old adults, it's safe to assume that the health benefits of helping and taking care of others also reach those of all ages. However, it's important to note that too much caregiving often has just the opposite effect. There's a clear link between too much caregiving and a number of negative physical and mental health consequences.

Reading, , contributes to happiness.