关于物体的重力、静摩擦力，下列说法正确的是（   ）

丽丽是个漂亮的女孩子，长得像动画片中的小天使。可是升入中学不久，她的脸上就开始出现了一些“小痘痘”。从此她对别人的目光特别敏感，心情也变得越来越不好。 这说明丽丽（    ）

    The bird and the tree are friends．The bird often sings songs in the tree．Autumn comes．The bird has to fly to the south．Spring comes.The bird comes back，but she can’t see the tree．Grass tell her some workers cut the tree down and took him to a factory．Then the bird flies to the factory．The workers told her they cut the tree into wood．They used the wood to make matches．Then they took the matches to a village．The bird flies to the village and sees a girl used the last match to make the fire．The bird sings a sad song to the fire．