First of all, I want to say that the second question does not exist, because it is a hypothesis, that is to say, if the underlying asset is positively related to the interest rate, when the market interest rate rises, the price of the underlying asset will also rise, and the futures contract bulls can immediately sell the contract for profit and reinvest at the current market interest rate (note that the interest rate at this time is the rising interest rate), but the forward contract can not be executed until it expires, and the price is agreed in the contract; When the market interest rate drops and the price of the underlying asset drops, the long position of the futures contract will lose money immediately because of the daily settlement system, but he can raise funds to supplement the margin according to the current market interest rate (reduced interest rate). The advantage of futures here is that they can be sold at any time.

Maybe I misunderstood. My understanding of your second question is as follows:

When A= 1, B= 1 is deduced. Now ask why A= 1 In this case, this problem does not exist, because this A= 1 is a premise assumption, and it cannot be said that B= 1 deduces A= 1, because when

If your question is not like this, send out the complete question and have a look.