填入合适的介词 Dear Sirs, Iron Nails We are interested (1)____ buying large quantities of Iron Nails (2) ____ all sizes and would be thankful if you could give us a quotation per metric ton CIF Lagos, Nigeria. It would also be appreciated if samples and a brochure could be forwarded to us. We used to purchase this article from other sources but we now prefer to buy from your corporation because we are given to understand that you are able to supply larger quantities (3) ____ more attractive prices. Besides, we have confidence (4) ____ the quality of Chinese products. We look forward to hearing (5) ____ you by return. Yours sincerely,