请你阅读下列短文,简要回答问题.

    On July 12th, 2009,  at 5 pm, a lot of fans  met  at  People's Square in   Shanghai.  They  performed

Michael Jackson's unfinished dance. For one minute, they sang and did the moon walk ( 太空步 )  to

remember Michael Jackson.

    This kind of phenomenon (现象) is called "flash mob (快闪族)". "Flash mob" is a group of people who meet in a public place to perform an activity for a short time. Sometimes all these people are friends, but

usually they are strangers (陌生人) and they find each other (彼此) on the Internet.

    "Flash mob" is very surprised and strange. One of the popular "flash mob" activities was in Manhattn,  

 New York City: Three hundred people met in a store and each of them told the shop assistant that they

would buy the same size sports shoes, and the shop assistant didn't know what to do.

1. What did a lot of fans do at People's Square in Shanghai?

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2. What is "flash mob"?

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3. Are people of "flash mob" usually strangers?

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4. Where do people find each other in a short time?

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5. What does the writer think of "flash mob"?

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