The first point to note is that neither the Bank of England nor the Treasury can do anything much to ________ the pound as long as the euro remains on the ropes.
句意：首先要注意的一点是，只要欧元的地位岌岌可危，英国央行和财政部就都没有办法保持英镑的稳定。retain有 “保持，稳定”之意，符合句意。reserve储备，保留。restrain控制，约朿。replace代替。