【单选题】A competitive firm uses two inputs, x and y. Total output is the square root of x times the square root of y. The price of x is 17 and the price of y is 11. The company minimizes its costs per unit of...
【简答题】阅读理解。 The old man is already sixty years old. But he has only fif birthdays. How is it? When is his birthday? Keys: His birthday is on Februar y 29th. It’s a leap(闰年) year every four years. So he ...