下列实验操作指定容器中的水，解释水的主要作用

有5条线段长度分别为1，3，4，5，7，从中任取三条为一组，它们一定能构成三角形的频率为（　　）

法国大革命先驱者卢梭说，一切法律之中最重要的法律，既不是刻在大理石上，也不是刻在铜表上，而是铭刻在公民的内心里。卢梭的观点对我国落实依法治国的启示是  （）

近代以来,三次科技革命对人类社会的发展产生了巨大影响。阅读下列材料:

材料一  英国煤产量示意图

材料二  一些工业发展的城市和工矿区人口密集、物流量大,煤的燃烧量急剧增加,大气污染的环境问题不断发生,如1873、1880、1882、1891、1892年,英国伦敦多次发生可怕的有毒烟雾事件。

——刘少康编著《环境与环境保护导论》

材料三  自然科学正在准备一次新的革命,蒸汽大王在前一世纪中翻转了整个世界,现在它的统治已到末日,另外一个大得无比的革命力量……将取而代之。

——马克思

材料四  第二次世界大战后,爱因斯坦多次发表谈话,“鉴于未来任何世界大战必将使用核武器,而这种武器威胁着人类的继续生存,我们敦促世界各国政府认识到并且公开承诺,它们的目的绝不能通过世界大战来达到”。“原子能可用于和平的、建设性的目的……而且无疑将是对人类的一大恩惠”。

请回答:

    A recently study found people's lives are made shorter in North China. It is showed the life expectancy(平均寿命) had been cut down by 5.5 years there. Researchers think that the heavy air pollution in China should be to blame. It's really the truth. Our government has already done something. However, it doesn't seem to work so well.

    “Air pollution in China is doing harm to people's health. The harm is much more serious than we can imagine,” said Chen Yuyu of Beijing University, one of researchers of this study.

    Dirty air brings serious problems in North China. In January this year, the air pollution was worse than that in other places. That was caused by rising temperature and waste gas from coal heating.

    Chinese government should strongly fight against air pollution. They should think of more proper ways to deal with the problem. People should be encouraged to take buses, ride bicycles or walk, instead of driving cars. The factories that pollute heavily should be closed.

    “We need to improve our environment, although it might be expensive. Protecting our environment means protecting ourselves,” Li Hongbin, another researcher of the study said.