《中华人民共和国劳动合同法》是规范劳动关系的一部重要法律。这部法律（  ）

①为维护劳动者的合法权益提供了法律保障

②明确了劳动合同双方当事人的权利和义务

③为构建和发展和谐稳定的劳动关系提供了法律依据

④有利于市场在劳动力资源配置中发挥主导作用

我们身旁的健身器材：____、____等。

词汇：

同素异形体　 ____；氨　 ____．铝 ____；合金　 ____；氯气　 ____；reducing agent ____；amphoteric ____；oxidation ____；Silicon ____；acid rain ____

阅读下面语篇并根据语篇内容回答问题
    A train stopped at a small station. A man on the train looked out of the window and saw a woman. The woman was selling cakes, and the people from the strain bought them. The man wanted to buy a cake, but the woman was far away from him. It was raining, and he didn't want to go out. Suddenly he saw a boy. The boy was walking on the flatform（月台）not far from him. “Come here.” He said to the boy, “Do you know how much each of the cakes is?” “Five cents（分）.” The boy answered. The man gave the boy ten cents and asked him to buy two cakes. “One is for me and the other is for you” he told the boy. Some minutes later, the boy came back. He was eating a cake. He gave the man five cents and said, “There was only one    cake left（剩下的）.”