I’d like to return this.
我想退掉它。

Can I have a refund?
能退給我錢嗎？

Could you alter this, please?
能改變這個嗎？

The waist needs taking in (letting out) by 3 centimeters.
腰需要收（放）3公分。

Could you make it longer (shorter)?
能做長（短）點嗎？

Does it take a long time?
要用很長時間嗎？

Can you make it a little earlier?
能早點做嗎？

I put money in this vending machine, but a coke didn’t come out.
我把錢放進(jìn)自動售貨機(jī)里，可是沒有可樂出來。