Please sign a copy of our Sales Contract No.156 enclosed here in duplicate and return to us for our file.
请会签第156号销售合同一式两份中的一份,将它寄回我方存档。
I've got a problem and as I don't know what to do I thought I'd write to you and ask for your advice.
我有一个问题,因为我不知道该怎么办。我想我最好写信给你,征求你的意见。