根据短文内容，选择最佳答案。 Every town in the United States has a post office. Some are very smalll, and you may find one in the corner of a shop.Others are large buildings. They are open five days a week from Monday through Friday. They are usually open from 8:30am to 4:30 pm. 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 at many different prices. From one cent to many dollars. If you are not sure how much postage (邮资) 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 letters far away, you shall use airmail envelopes (航空信封). Remember that postage (邮资) 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 (邮资) for a postcard is about half that of a letter. The postcards, however, are not to be sent outside the country. Letters are an easy and cheap way to keep in touch with people in many different countries. 1. The passage tells us that we can find _______ easily in the United States. [     ] A. post offices B. large buildings C. small shops D. different banks 2. The post offices in the United States are open _______ a day. [     ] A. seven hours B. six hours C. five hours D. eight hours 3. If you are not sure how much postage (邮资) is for your letter, you can _______. [     ] A. go and buy stamps from the machine in the post office B. send a cheap postcard instead of your letter C. get in touch with someone you know in the post office D. ask the man or the woman in the post office for help. 4. The price of postage (邮资) for _______ is more expensive. [     ] A. a beautiful postcard B. a letter written on envelope C. a letter by airmail D. a postcard with pictures 5. The passage tells us something about in the USA. [     ] A. the post B. the postage (邮资) C. letters D. postcards