●nventory investment(存货投资) The change in the quantity of goods that firms hold in storage,including materials and supplies,work in process (加工中的产品)，and finished goods. Neoclassical model of investment The theory according to which investment depends on the deviation of the marginal product of capital from the cost of capital. ⚫ Inventory investment (存货投资) The change in the quantity of goods that firms hold in storage, including materials and supplies, work in process (加工中的产品), and finished goods. ⚫ Neoclassical model of investment The theory according to which investment depends on the deviation of the marginal product of capital from the cost of capital