This offer is firm subject to your acceptance reaching us not later than December 15.
此报盘为实盘,但以我方在12月15日前收到你方答复为准。
I'm very sorry. Usually I'm very careful. I have never lost a book before. It won't happen again.
“很对不起。通常我是非常小心的。我以前从来没有丢过书。这样的事不会再发生了。”