心理功能主要是由____实现的。

    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.

某学习小组对一辆在平直公路上做直线运动的小车进行观测研究．他们记录了小车在某段时间内通过的路程与所用的时间，并根据记录的数据绘制了路程与时间的关系图象，如图所示．根据图象可以判断（　　）