完形填空

       Sometimes it is impossible to deliver（投递）all the mail that arrives at the post office. Perhaps there is an1  mailing address and there is no return address. The post office cannot just   2  the mail, so it becomes “dead mail”. Dead mail is   3to one of the U.S. Post Service’s in Atlanta, New York, and San Francisco. Seventy-five million pieces of mail can be put in these offices in one year.

      There the workers of the dead mail offices have   4 ways to deal with all of these pieces of dead mail. First of all, they look for something  5  that can help them deliver the mail; they open packages, expecting that something   6 will show where the package came from or is going to. Dead mail will also be listed on a   7   so that people can call in and check to see if a missing thing is there on the screen. However, all of this mail cannot simply be   8 forever; there is just too much of it. When a lot of dead mail comes together, the dead mail offices hold public auctions (拍卖). Every three months, some people who are   9   are invited to the offices with objects（物品） found in dead mail packages and they are sold to the  10  bidder (出价者).