请英语经济达人解答一下几道经济问题

请英语经济达人解答一下几道经济问题
1.Which of the following costs is independent of output?
Answer
Variable costs.
Total costs.
Marginal costs.
Fixed costs.
2 Implicit cost refers to:
the amount a firm receives for selling its product or service.
any increase in the value of the assets owned by the firm.
the opportunity cost of factors of production provided by the owners of the firm.
explicit payments to the factors of production.
3The relationship between the quantity of inputs and the quantity of output is called the:
production function.
average product.
marginal product.
law of diminishing returns.
4 In the short run:
all inputs are variable.
firms can use any input combination they want.
firms can choose among all possible production techniques.
some inputs are fixed.
5 Costs that are spent and cannot be changed in the period of time under consideration are called:
variable costs.
total costs.
marginal costs.
ed costs.
每道题4个选项