题目

Most people want to be happy, but few know how to find happiness. Money and success alone do not bring lasting happiness. Aristotle, a Greek thinker, said, Happiness depends upon ourselves. In other words, we make our own happiness. Here are a few suggestions to help you be happier.  The first secret of happiness is to enjoy the simple things in life. Too often, we spend too much time thinking about the future-for example, getting into college or getting a good job-that we fail to enjoy the present. You should enjoy life's simple pleasures, such as reading a good book, listening to your favor13．关于力的概念，下列说法正确的是（　　）A．一个受力物体不可能受到两个施力物体的作用力B．只有相互接触的物体之间才可能存在力的作用C．一个受力物体可以不对其他物体施力D．力是物体对物体的作用