9. I do not know how to fill out the exchange form.
我不知道怎样填写兑换单。
还能这样说：
Can you give me some help to finish the exchange form?
Could you tell me what I should do to fill in the exchange form?
谚语：
A leopard can't change its spots.
积习难改。
10. Opening a checking account may be economical for you.
对您来说，开立一个支票账户是实惠的。
还能这样说：
It will be better for you to open a checking account.
That checking account will be affordable for you.
应用解析：
be economical of one's time 节省时间;
an economical housewife 一个节俭的家庭主妇
11. Good morning. Are you being attended to?
您好，有人接待您了吗?
还能这样说：
Good morning. Have you been waited on?
Good morning. Are you being helped?
应用解析：
not attend 无人值班;
attended substation 值班员变电所
12. You should fill in a form here first.
您首先需要在这儿填个表格。
还能这样说：
Please fill out a form here first.
First, you need to fill out a form.
谚语：
The cask savors of the first fill.
先入为主。