when was bp oil spill As hicks income concept did not specify what is called "equal wealth", and thus the income concept formed the basis of many debates concept, and the theory of accounting earnings, especially the capital preservation theory has a great influence. In accounting, people used to call "maintaining the same level of affluence" as capital preservation. Xpoint fills the cost and cost gap between high speed and high cost DRAM and low cost NAND. Does this technology engulf DRAM and NAND markets? Customers who purchase a large number of Xpoint chip/drives may purchase fewer DRAM chips and NAND chips/drives. Hybrid cars, which add an internal combustion engine to pure electric vehicles, aim to reduce the pollution of cars and improve the mileage of pure electric vehicles. Hybrid vehicles have serial and parallel structure.