Consider a stock futures contract with a term of 24 months. The current price of the stock is 40 yuan. Assume that the risk-free interest rate (continuous compound interest) is 12% per year for all maturity dates.

(1) If the stock does not pay dividends, calculate the price of the futures contract.

(2) If the stock pays dividends at 3 months, 6 months, 9 months, December, 15 months and 20 months respectively, the dividend income is 4 yuan , try to calculate the price of the futures contract.

(3) If the stock pays a bonus rate of 4%, calculate the price of the futures contract.

(4) If an investment commodity metal copper futures: T = 15 months, s = 50 yuan, r = 12%, the holding copper will pay the storage cost of 3 yuan at 3 months, 9 months, 12 months and 15 months, try to calculate the price of the metal copper futures;