2. Click this button to add a new constant. 单击此按钮可添加一个新常量。
3. It is found that the type of each departmental effect is not constant, but various with the development of economy. 研究发现：各部门的作用类型并非永远是固定的，将随着经济的发展而发生类型转变。
1. a quantity that does not vary
2. a number representing a quantity assumed to have a fixed value in a specified mathematical context adj.
1. persistent in occurrence and unvarying in nature
2. continually recurring or continuing without interruption
3. steadfast in purpose or devotion or affection
4. uninterrupted in time and indefinitely long continuing