Theory of Demand

3. To change with time or a similar parameter.
6. The highest limit.
8. Pertaining only to a part of something; partial.
9. An option; a decision; an opportunity to choose or select something.
10. To influence or alter.
12. To support (someone), to back up or assist (someone) in an action.
15. Connection or association; the condition of being related.
17. To hang down; to be sustained by being fastened or attached to something above.
18. The state or condition of being useful; usefulness.
19. A standard measure of a quantity.
20. To go or come after in physical space.

1. To get hold of; to gain possession of, to procure; to acquire, in any way.
2. The act or process of putting in; infusion.
4. To authenticate by means of belief; to surmise; to suppose to be true, especially without proof.
5. The act of improving; advancement or growth; promotion in desirable qualities; progress toward what is better; melioration; as, the improvement of the mind, of land, roads, etc.
7. To advance, promote (someone)
11. Act of expending or paying out.
13. Unchanged through time or space; permanent.
14. A wallet, purse or bag.
16. Supplemental or added to something.