precision tune oil change In economic terms, the benefits of holding any two currencies should be equal in the equilibrium of the foreign exchange market, which is: Ri=Rj (interest rate parity). Here, R stands for yield, and I and j represent currencies of different countries. If the benefits of holding two currencies are unequal, you will have A arbitrage: buy A kind of foreign exchange and sell B foreign exchange. 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.