I was wondering if i could...

I was wondering if I could... 我不知道能否（礼貌询问/请求）

I wonder if... 我在想是否

No wonder 难怪

I was wondering if I could exchange them for another pair.

I was wondering if I could borrow your car.

I wonder if i did the right thing, giving him away.

No wonder she's angry.

Exchange 交换    Receipt 收据

exchange sth for sth 以某物换某物

exchange sth 交换某物

I exchange those trousers for a lager size.

Since you are a loyal customer, I'll exchange this box for another one.

They exchanged phone numbers.

Do you have a receipt?

loral customer 老顾客

give sth back 退回某物

take sth back 收回某物

return sth 退回某物

She couldn't give the painting back

The store said they won't take it back because you signed for it

I'm returning the ring

I want to return this