An adjustment refusal message requires your best communication skills __14__ it is bad news to the receiver. You have to refuse the claim and retain the customer 15 .
答案：(C) at the same time
at the same time（同時）表示「你必須拒絕客戶的請求，同時還要留住這位客戶」，符合「拒絕」與「留客」這兩個看似矛盾任務同時進行的語意。by and large（大體上）、over and over（一再地）、for the same reason（基於同樣的理由）都不符合這種「同時兼顧兩件事」的語意。
四個選項都是三四個字的片語，你會挑一個中文讀起來最順的擺進去。
這是邏輯勾環：要判斷的是同一句裡兩件事之間的關係。整句是 You have to refuse the claim and retain the customer ______.（你必須拒絕這項索賠，並且______留住這位客戶）。拒絕與留住是兩件方向相反的事，卻要在同一封信裡一起做到，這種「一邊……一邊……、然而同時」的關係就是 at the same time。這個片語除了字面的「同時」，還有一層轉折的用法——先承認前面那件事，再提出一件與它拉扯的事，中文常譯成「但另一方面」。填進去讀成 refuse the claim and retain the customer at the same time（拒絕索賠，同時又要把客戶留住）。
over and over（一再地、反覆地）講的是次數，留住客戶不是一件反覆做的事；for the same reason（基於同樣的理由）要求前面先出現過一個理由，這一句前面沒有；by and large（大體而言）是對整體情況下評語，接在這裡讀不出與「拒絕」的拉扯。
at the same time（同時；但另一方面）、over and over（一再地、反覆地）、for the same reason（基於同樣的理由）、retain a customer（留住客戶）、refuse a claim（拒絕索賠要求）、handle a claim（處理索賠）。
Handling customer claims is a common task for most business firms. These claims include requests to exchange merchandise, requests for refunds, requests that work 11, and other requests for adjustments. Most of these claims are approved because they are legitimate.
However, some requests for adjustment must be 12, and an adjustment refusal message must be sent. Adjustment refusals are negative messages for the customer. They are necessary when the customer is 13 or when the vendor has done all that can reasonably or legally be expected.
An adjustment refusal message requires your best communication skills 14 it is bad news to the receiver. You have to refuse the claim and retain the customer 15. You may refuse the request for adjustment and even try to sell the customer more merchandise or service. All this is happening when the customer is probably angry, disappointed, or inconvenienced.