根据上下文补全对话    

Jack: Hello!    1    

Tom: Sure. Wait a minute.

Mary: Hello.    2     

Jack: This is Jack speaking. Mary, my mother is ill.  So I must stay at home to look after her.

Mary:     3     What can I do for you?

Jack: Would you like to tell Miss Gao that I can't go to school this afternoon?

Mary:     4    

Jack: Thanks.

Mary:     5    

1.           2.             3.             4.             5.            

先导型减压阀的主阀和导阀弹簧一般：（）

A.主阀硬导阀软

B.主阀软导阀硬

C.主阀和导阀都软

D.主阀和导阀都硬