Tornadoes are nature's most violent storms, which can cause deaths and destroy a neighborhood in seconds. A tornado appears as a funnel-shaped (漏斗状) cloud from a thunderstorm to the ground with whirling (飞快移动) winds that can reach 300 miles per hour. Damage paths can be over one mile wide and 50 miles long. Every state is at some risk from this disaster.

    Some tornadoes can be seen clearly, while rain or nearby low-hanging clouds obscure others. At many times, tornadoes develop so rapidly that little, if any, advance warning is possible.

    Before a tornado hits, the air may become very still. A cloud of debris (散片) can mark the location of a tornado even if a funnel can not be seen. Tornadoes generally occur near the edge of a thunderstorm, when the strong wind may die down. It is not uncommon to see clear, sunlit skies behind a tornado.

The following are facts about tornadoes:

    The average forward speed of a tornado is 30 MPH, but may also vary from still to 70 MPH. Debris is picked up or a cloud forms in the funnel.

    The average tornado moves from southwest to northeast, but tornadoes have been known to move in any direction. Tornadoes are most often reported east of the Rocky Mountains during spring and summer months.

    Tornadoes can happen together with tropical storms and hurricanes as they move onto land. Waterspouts are tornadoes that form over water.

    The tornado season in the southern states of America is March through May; in the northern states, it is late spring through early summer. Tornadoes are most likely to occur between 3 p.m. and 9 p.m., but can occur at any time.

下列函数中，是一次函数的有（　　）
（1）y=πx  （2）y=2x-1   （3）y=$\frac{1}{x}$（4）y=2-3x   （5）y=x²-1．

材料一：战后初期西欧各国经济的困难引起了政局的激烈动荡。饥寒交迫的人民群众对本国政府的不满和反抗情绪与日俱增，阶级矛盾急剧上升。1947年上半年，法、英、意、比等西欧国家的罢工浪潮和工人运动风起云涌。在反法西斯斗争中得到锻炼和成长的西欧各国共产党在群众中的影响不断扩大，威望越来越高。尤其是法共和意共，在战后初期的大选中，法共获选票1/4，成为国会中第一大党；意共获得选票达1/3。

——斯帕尼尔《第二次世界大战后美国的外交政策》

材料二：图1：英国宣传马歇尔计划的海报。一位英国妇女脚踩着高跷，两只高跷上分别写着“MARSHALL”（马歇尔）和“AID”（援助），她前面的英文是“BETTER STANDARD OF LIFE ”（更美好的生活）。

图2：1947年苏联某杂志刊登的“美国最新战车”

材料三：在美国（马歇尔计划）的要求下，1947年7月，英、法等16个国家成立了“欧洲经济合作委员会”，后改为常设机构——“欧洲经济合作组织”（OEEC）……西欧国家为接受马歇尔计划的援助而成立的一系列经济组织，都不同程度地冲破了原来民族国家的界限，加强了西欧各国的经济联系。

——摘编自王国范《试论马歇尔计划对战后初期欧洲的影响》

阅读理解。

      汽车和路面，就像鱼和水的关系一样密切。作为公路的”铠甲”——路面，天天展现在司机的眼前。可是这层”铠甲”，不是黑颜色的沥青路，就是白颜色的水泥路。单调的路面颜色，会使长时间行车的司机感到疲劳。能否把公路也搞得丰富多彩一些呢?能。新研究出来的彩色路面就能够解决这个问题。铺设这种路面像绘画调色一样，把不同的色彩掺进黑颜色沥青材料里面，便铺出红、蓝、黄、绿等不同颜色的路面来。彩色路面像一本大书，它会告诉司机：红色——前面有交叉路口和居民点；蓝色——附近有小学校，注意小学生穿行马路；黄色——不准开快车，限制车速……。这种路面可以消除司机的疲劳，对安全行车，减少交通事故非常有效。彩色路面还可以结合周围建筑和环境来美化城市。我国天津市铺筑了国内第一条褐红色沥青路面，色调柔和，给人以舒适的感觉。如果居民区中心有蓝色的广场，沿着湖边有绿色小路，儿童游戏场铺上橙黄色地面，那该是多美丽呀。

现在,每逢嫁娶、乔迁、生子,有些人总要选个“黄道吉日”,祈求神灵保佑平安、幸福。从哲学角度看,这些人的观念属于（  ）