请翻译以下这段商务信函文字，进一步体会“7C原则”：Thank you for your letter of April the 18th. We regret that we cannot accept your counter-offer. We must point out that the falling market here leaves us little or no margin of profit. We must ask you for a keener price in respect to future orders. At present the best discount offered for a quantity of 200 is 55. Our current situation leaves us little room to bargain. We hope you will reconsider our offer.