判断对错.

约分和通分都是改变分子、分母的大小，分数大小不变．

    Mayme Clayton collected books， magazines and letters written by African Americans. Her son， Avery Clayton， thought her collection was important. Unlike most books， these were rare and hard to find. They were written by writers who helped shape African American culture.

    One book in the collection was written by Phillis Wheatley. Wheatley was a slave who wrote poetry. She was the first African American to publish a book. Wheatley herself signed (签名) the book in the Claytons' collection. No one else owns a copy signed by Phillis Wheatley.

    By the time she passed away at age 83， Mrs. Clayton had more than 30，000 books by or about black people. Her collection also includes papers about slaves， photographs， movies， sheet music， and personal letters by black leaders and artists. It is one of the biggest personal collections of African American history and culture in the United States.

    Avery Clayton's dream was to create a museum for his mother's treasures.  Scholars say that Mrs. Clayton's collection is very important. Without her work， part of African American heritage (遗产) would have been lost. “We didn't know these things existed，” says Sara Hadron of California's Huntington Library.

    The collections new home is likely to be in Culver City， California. Part of Avery Clayton's dream is to share the cultural riches his mother collected with others. He especially wants children to have a chance to see the collection. “ At present African American culture is being explained by pop culture，” he says， “ It's important to offer a more complete picture.”

（D）

    Every boy wants to find treasure．And Tom was no different.  One summer day Tom told Huck about his idea．

    "Where can we look for treasure？"asked Huck．

    "It's hidden on islands，under dead trees，but mostly under the floors in haunted（闹鬼的） houses．"

    So，one Saturday afternoon Tom and his friend went to look for treasure as the haunted house on Cardiff Hill．It was a quiet and lonely which made the boys feel very frightened．They entered quietly，and explored downstairs．Everything was old，broken and dirty．They threw their tools in a corner and walked upstairs，but there was nothing there．They were just about to go downstairs and start digging when Tom stopped．

    "What is it？"whispered Huck，going white with fright．

    "Keep quiet! There's someone downstairs．"

    The boys lay down，looking through the holes in the wooden floor．There were two men downstairs．One was an old Spaniard in a wide sombrero hat and the other was duty and unpleasant﹣looking．

    Tom and Hack shook with fear when they heard the Spaniard speak because they found it was Injun Joe He said，

    "It's time for us to move，partner．What will we do with the 650formtherobbery（抢劫）？""Let'skeep30each and leave the bag here．"

    The dirty man went to the fireplace and moved a stone．Then he lifted out a bag full of money and look out some coins．The two boys forgot all their fears when they saw there was real treasure downstairs．

    Then Indian Joe started digging a hole with his knife and the knife hit something．

    "What is it？"asked the other man．

    "It's a box，"said Indian Joe．And he put in his hand and pulled out a handful of gold coins．The other man found the boys'tools，and they soon pulled out the box．

    "Where's thousands of dollars in there，"Said Indian Joe．

    "The Murrell Gang used this area one summer，"said his partner．

    "They most have hidden their money here．"

    "What will we do with this，Joe？Will we bury（埋）it again？"

    "No，someone might find it，"said Indian Joe．"Let's bury it in the member two den（巢穴）．"

    Tom and Huck got up as soon as the two men left．They decided to watch out for the"man in the sombrero"when he came to town and find out where the member two den was．