在物理习题中,经常会出现求某物理量的变化范围,而不少教师在得到结果时往往将该物理量变化范围写成从某值到某值.这样写法,无法看出该物理量的取值范围是否含上限或下限的数值.实际上,我们在教学中应针对具体的问题,用不等式的形式写出物理量的取值范围.下面,笔者就以一些例题加以说明. In physics exercises, there is often a range of changes to a certain physical quantity, and many teachers often write the range of changes in physical quantity from a certain value to a certain value when the results are obtained. In this way, it cannot be seen whether the range of values ​​of the physical quantity is Including the upper or lower limit value. In fact, we should use the inequalities to write the range of the physical quantity in the teaching for the specific problem. In the following, the author will explain with some examples.