“如果你相信你读到的任何东西，那么不如不读书。”这句话给我们的启示是（    ）

下列因式分解正确的是（   ）

在中国传统文化艺术中，“鱼”和“水”的图案是繁荣与收获的象征，“鱼”有吉庆有余、年年有余的蕴涵．那么水中生活的鱼类能在水中游泳的动力来自于（　　）

    There are three people in my family, my parents and I. My name is Li Yan. I 'm a middle school1.

    I am thirteen years old. I 'm from China, so I can speak2. I can speak a little English, too. These are my 3 .My father is a teacher in a 4 . He can speak Chinese, English and French. He teaches English. He likes 5. He often goes swimming and plays table tennis on Sunday.

    My6  is a manager. She works in a factory.7only speaks Chinese. She likes music and she can8very well. She often sings old songs. She likes white best, so her favourite season is9because it snows. Look! Here is my 10. Its name is Mimi. It is a very cute cat and I like to play with it.

100g的 ${}_{83}^{210}$ Bi经过10天后衰变了75g，则 ${}_{83}^{210}$ Bi的半衰期是（   ）