We are glad to receive your order of yesterday,_______ regret th

We are glad to receive your order of yesterday,_______ regret that we can not supply the end of May.
A、but, by
B、and,by
C、but, for
D、and,for
【正确答案】：A
【题目解析】：regret空格前后表示转折，用 but；by the end of May表示到五月底。句意：很高兴收到您昨天的订单，但很遗憾，我方无法在5月底前提供货物。