Some of the low-end Made-in-China mechanical-electronic products are not selling well in export market as compared with what are termed as high-end ones.

A．on export market

B．in exporting market

C．in exported market

D．in the export market

若某投资者以4 500元/吨的价格买入1手大豆期货合约，为了防止损失，立即下达1份止损单，价格定于4 480元/吨，则下列操作合理的有( )。

A．当该合约市场价格下跌到4 460元/吨时，下达1份止损单，价格定于4 470元/吨

B．当该合约市场价格上涨到4 510元/时，下达1份止损单，价格定于4 520元/吨

C．当该合约市场价格上涨到4 530元/吨时，下达1份止损单，价格定于4 520形吨

D．当该合约市场价格下跌到4 480元/吨时，立即将该合约卖出