通讀下面的短文，掌握其大意。然后，從每小題的四個選擇項中選出可填入相應空白處的最佳選項.

21.（）

• A、covered
  
  

• B、named
  
  

• C、taken
  
  

• D、.acted
  
  

提示:Henry準備去上海開會，打電話到航空公司訂票，工作人員Lillian 接聽了電話。

(L= Lillian; H = Henry)

L: Hello! This is Air China.    51     

H: Hello. I'd like to book a flight from Beijing to Shanghai.

L: Sure.   52    ?

H: This Saturday morning July 12.

L: OK. How many tickets?

H:   53   .

L: So, that's one ticket from Beijing to Shanghai.

H:    54   ?

L: Well, that will be 1 ,030 yuan.

H: OK. Can I book that now?

L: Certainly.

H:   55   ?

L: You' re welcome.

Bill is not in the office. He（）to the library an hour ago.

• A、went
  
  

• B、 has gone
  
  

• C、Would go
  
  

• D、has been