有两个国家A和B，在休谟所描述的金本位制下，如果B国的收入向A国转移，请分析两国是如何再度实现其国际收支平衡的。
Under a gold standard of the kind analyzed by Hume，describe how balance of payments equilibrium between two countries，A and B，would be restored after a transfer of income from B to A.