―Somebody wants you on the telephone.

―       no one knows I’m here.

       A．For                     B．And                    C．But                     D．So

--Somebody wants you on the telephone.

--______ no one knows I'm here.

[　　]

——Somebody wants you on the telephone.

——__________ no one knows I'm here,

[　　]

－Somebody wants you on the telephone.

－________ no one knows I'm here.

[　　]