题目

Psychology（心理学）tells us that many people hate to take risks. But it is good for us to take risks, especially (尤其)when the risk is to achieve a desired result. In that way, we become stronger and braver. Our human nature should be to take risks, but some people just sit and wish they didn’t have the fear（恐惧）to move on. This is because of one or two failures in their lives. Please step out and don’t let the past hold you back from living life to the fullest. Move forward and move on! In studying the psychology of taking risks, we find that human nature provides(提供) 一个实验小组在“探究弹力和弹簧伸长的关系”的实验中，使用两条不同的轻质弹簧a和b，得到弹力与弹簧长度的图象如图所示．下列表述正确的是（ ）A．a的原长比b的长B．a的劲度系数比b的大C．a的劲度系数比b的小D．测得的弹力与弹簧的长度成正比