The investment of securities provides an important means for the central bank to conduct financial macro-control, which is of great significance to the sustainable and efficient development of the national economy. Most western interest-rate determinism focuses on the analysis of supply and demand comparisons, arguing that interest rates are a price. The difference lies in what supply and demand determines interest rates. For example, Marshall's real interest rate theory emphasizes the real factors of non-monetary factors - productivity and the role of economy in determining interest rate decisions. Productivity is expressed by marginal propensity to invest, and the marginal propensity to save is expressed. The report said: “These pay penalties exist despite the Agency Worker Regulations 2010 which gives those with 12 weeks-plus of continuous service in the workplace pay parity with comparable employees.” It is generally believed that the v-shaped engine is a relatively advanced engine, which also becomes a symbol of the sedan grade. At present, the most common engines are the straight-line 4 cylinder (L4) and v-type 6 cylinder (V6) engine. In general, the V6 engine has a higher displacement than L4, and the V6 engine runs smoothly and quietly than the L4 engine. A V6 engine is usually mounted on a mid-grade sedan. A car that has been modified to transport specialized goods.