英文傳意翻譯help!

直譯 : I don't know the purpose of this thing. Someone just bought it from us.

但是, 這東西是由你賣給別人. 若就此直接說你不知道這東西, 會有點奇怪.

除非, 你只是該店的收銀員. (注意 : 銷貨員是應該會熟悉產品的.)

因此, 這樣說會比較好 :

I am only a cashier of the shop. So, I don't know the purpose of this thing. Someone just bought it from us.

I don't know what it is used for; it is something that someone has ordered from us.

I do not know what purpose, we only heard of a person to buy.