Long strategy: If the market interest rate is expected to fall, or the bond yield is expected to fall within a certain period of validity, the bond price will rise, then you can choose a long strategy and buy treasury bond futures contracts in the expectation that the futures price will rise and make a profit. Item a is correct. Short-selling strategy: If the market interest rate is expected to rise or the bond yield is expected to rise and the bond price falls, you can choose short-selling strategy and sell the treasury bond futures contract, expecting the futures price to fall and make a profit. Item d is correct. So the answer to this question is AD.