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    Are you a big fan of E.T. (Extraterrestrial) or aliens? Then you should read Extraterrestrial Civilizations (《地球以外的文明世界》) by American writer Isaac Asimov (1920-1992). In his 1979 book, Asimov looked at whether there is life beyond the Earth. He also talked about how we might be able tocommunicate with aliens someday. Asimov even told us that there are possibly about 500,000 civilizations (文明) in the galaxy (银河系). The book may be a little out of fashion since it came out in the 70s. But you'll still enjoy the good reasoning (推理) and imagination of it. Asimov was a science fiction (科幻故事) master. His most famous works talk about the relationship between robots and humankind.

    Mr. King was the manager of a hotel. One weekend all the hotels in the city were full because there was a large meeting. On Friday night, three men came into the hotel and asked for rooms. Mr. King said there were no rooms ready because of the meeting. The men were unhappy.

    Mr. King wanted to help them. He remembered that Room 418, a very small room, was empty. He asked them if they would share a room. The three men said they would. Mr. King said the room would be thirty dollars: ten for each one. Each man gave him the money and then went up to the room.

    Mr. King soon began to feel sorry. "Thirty dollars is a lot to ask as price for that small room. " he thought. He called his assistant over and said, "Here is five dollars. Take it to the men in Room 418. I asked too much for their room."

    The assistant took the money. While he was on the way there, he started to think, "How can three men divide five dollars? I'll give them each only one dollar and keep the two dollars for myself. The men will be happy to get something back, and Mr. King will never know. " So the assistant returned one dollar to each man.

    Each man had at first paid ten dollars. After the assistant returned them one dollar each, each had paid nine. There were three men, $ 9 ×3 = $ 27. The assistant kept $ 2. $ 27 + $ 2 = $ 29

    Where is the missing dollar?

    When I first came to New York, I didn't have many friends. I got upset easily. Luckily, one of my co-workers (同事), Frank, took great care of me. Actually, he changed me.

    I used to be shy. I had a hard time talking Io strangers. Frank knew it.  And he helped me deal with it.

    One day we were at a restaurant.  I dropped a piece of pizza on my shirt while eating. Frank told me to borrow a Tide pen (去污笔) from someone. I was nervous, but Frank encouraged me. So I went to ask for help. In the end, I was not only able Io clean my shirt, but also made friends with a stranger.  It was a good start for me.  I became more and more confident (自信的).

    Frank was optimistic about life. He always finds a way to change the bad things into something good.

    Because of a new job, I moved to a new city. Frank and I communicated with each other less and less. Then, one day, I got a call from a friend. Frank had passed away. It was one of the worst moments in my life. There was nothing I could do to deal with my sorrow (悲伤) except go lo sleep.

    I looked at a lot of videos about Frank. At the end of one video, Frank said, "After the rain, the sun shines through the clouds." I remembered Frank's optimism. Then I stopped crying. I decided to smile a bit wider and love fife more.

    O. Henry was a great writer. His pen name was O. Henry and his real name was William Sydney Porter. He was born in North Carolina in 1862. When he was about 20, he went to Texas, where he tried different jobs. He first worked on a newspaper, and then in a bank. When some money went missing from the bank, some people thought he was the thief, so he was sent to prison(监狱). During the three years there, he learned to write short stories. After he got out of the prison, he went to New York and went on writing. He wrote mostly about New York and the life of the poor people there. And people liked his stories very much.

    It seems very natural that if you have two dollars and add two dollars to them, you have four dollars. But do you know it too men millions of years to be able to think so? In fact, one of the most difficult things to teach children is the idea of numbers.

    In ancient times, when a man wanted to tell how many animals he owned. he had no system(系统) of numbers to use. He put a stone into a bag for each animal. The more animals, the more stones he had. It may explain why the word "calculate" comes from the Latin word "calculus", "calculus" means "stone."

    Then, man used lines to count. People would just draw a line for each thing they wanted to count, but they had no word to tell the number.

    Later on, people used fingers. Again we have word that goes back to this. The word "digit" comes from the Latin word "digitus". It means "finger"! And the fact that we have 10 fingers led to the use of 10 in the system of numbers.

    The number system we use today was invented by the Hindus in India thousands of years ago and was brought to Europe during 8^th to 11^th by Arab traders(商人). In this system, people count things with ten numbers. 1. 2.3.4.5.6.7.8.9.and 0. It is decimal system(十进制), that is, it is built on the base of 10.