6．听下面一段材料，回答第15至第17题．
15．Wnere does the conversation probably take place？
A．At a Lost and Found Office．
B．In a supermarket．
C．In a bookshop．
16．What was the man doing at about 8：00this morning？
A．Buying books
B．Take a taxi．
C．Looking for his bag
17．What do we know about the man's bag？
A．It's expensive．
B．It's large．
C．It's black．
