Strange things happened in Tangshan. ____ three days, water in the wells kept ____ (rise) and falling. ____ (smell) gas came out from the cracks of wells. Animals became ____ (nerve). There were other signs of an earthquake but the people thought little of these events. At 3: 42 a. m., everything began to shake. The world seemed ____ (be) at an end. One-third of the nation felt the ____ (great) earthquake. In fifteen seconds the city lay ruins. Two-thirds of the people died or ____ (injure). Thousands of families were killed and many children were left ____ parents. Then later that afternoon, ____ big quake shook Tangshan. People began to wonder how long the disaster would last. ____ all hope was not lost. Soldiers came to help the rescue work. Slowly, the city began to breathe again.

①推动人类思维和文化的发展           
②推动生产关系和社会制度的变革

③否定一切传统的观念和思想           
④推动社会生产力的发展

C、H、N三种化学元素的质量分数共占人体化学成分的73%左右，而这三种元素在组成岩石圈的化学成分中，质量分数不到1%，这个事实说明（　　）

如图在坐标系xOy里，有质量为m，电荷量为+q的粒子从原点O沿y轴正方向以初速度v₀射出，现要求该粒子能通过点P（l，﹣d），可通过在粒子运动的空间范围内加适当的“场”来实现，粒子重力忽略不计（静电力常量为k）

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