13．Listen to the passage and tell whether the following statements are true or false （判断下列句子是否符合你听到的内容，符合的用"T"表示，不符合的用"F"表示）
15．The smallest post office in the USA has only one room with no clerks．
16．The post offices in the USA are usually open from 8：30to 4：30on weekdays．
17．The United States Postal Service is the largest company in the world．
18．There are more than 40，000post offices throughout the United States．
19．The post offices in the United States deal with more mails than those in Japan．
20．The passage mainly tells about the history of the post office in the United States．
