About a month. Please fill out this customs declaration form.

大约一个月，请填这份海关申报书。

I'll just need to fill out a customs declaration form.

我只需要填写一份报关单。

Good afternoon. May I have a look at your passport and customs declaration form?

下午好。请出示护照和报关申请表。

A " customs declaration form" is a form – a piece of paper that says this is what is in this package.

“报关单”是一种表格——一张纸，上面写着这是包裹中的物品。