阐述使用虚位移处理具体问题可以分解为三步: 1) 对一个具体的物理问题，给出自变量虚位移的定义; 2) 对这个问题需要的函数，由于自变量的虚位移产生的变化; 3) 对相关函数加上物理要求.经过这三步之后，才能给出物理上合理的结果.而其中的第二步，体现了其非真实性.

Virtual displacement is an important physical concept in physics.For exaggerating the role of the non-reality in applications of the virtual displacement，we analyze how the virtual displacement is applied，which can be divided into three steps: 1) for a given physical problem，the definition of virtual displacement of a variable is introduced; 2) the variation of a mathematical function along the change of the virtual displacement is given，which is not necessarily compatible with physics principles; 3) with imposing physical conditions on the mathematical function，the physics consequence is resulted.