Average total cost 平均总成本
Total cost divided by the quantity of output
Average variable cost 平均可变成本
Variables costs divided by the quantity of output
Accelerator 加速数
the effect on GDP of the increase in investment that results from an increase in output. For instance, the greater output leads a firm to believe that the demand for its products will rise in the future; the resulting increase in investment leads to growth in output and still further increases in investment, accelerating the expansion of the economy
Acquired endowments 后天禀赋
resources a country builds for itself, like a network of roads or an educated population