Q: Lock after the interest rate calculated? A single lock that is at the same time hold more than one single is buying contracts and a Put single that sell contracts, spreads of more than a single prefix is investors need to pay or interest rate received. For example: buy a gold contract need to pay an interest rate of 3%, sell a gold contracts may receive an interest rate of 0%, so a single lock will be required to pay interest rates of 3%, and the method of calculating interest may refer IV.