Every town in the United States has a post office. Some are very small, and you may also find them in the corner of a shop. Others are larger buildings. They are open five days a week and on Saturday mornings. From Monday through Friday they are usually open from 8:30 a. m. to 4:30 p. m. .
If you know how much the postage(邮资)is for your letter, you can buy stamps at any window. In some post offices you can buy stamps from machines. Stamps are sold many different prices, from one cent to many dollars. If you are not sure how much postage is for your letter, you may ask the man or the woman in the post office for help. He or she will give you the stamps you need. If you are sending your letter far away, you should use airmail envelopes(航空信封). Remember that postage will be more expensive for a letter to be sent outside the country.
At a post office you can also buy postcards. A postcard is cheaper than a letter. Usually the price of postage for a postcard is about haft that of a letter. The postcards that you buy at a post office do not have pictures. However, also they are not to be sent outside the country.
If you are not sure how much postage is for your letter, you can ______ .