We believe that we will make a big success in promoting these toys throughout the season.Therefore， we have decided to place a large order（）you.

We believe that we will make a big success in promoting these toys throughout the season.Therefore， we have decided to place a large order（）you.
正确答案：with
解析:本题考查词组with sb.的用法，译为“向某人”。 全句意思是：相信我们双方将会在本季成功促销这些玩具。因此，我方决定向贵方下一笔大订单。