We will go out for a picnic（）it doesn't rain tomorrow.

• A、if
  
  

• B、after
  
  

• C、 that
  
  

• D、though
  
  

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.

Could you please（）why you are so late today?

• A、explained
  
  

• B、explain
  
  

• C、to explain
  
  

• D、explaining