—I really don’t know how to thank you enough .

    —       .

       A．No problem           B．Think nothing of it

       C．Not at all         D．It doesn’t matter 

—I really don’t know how to thank you enough .

—       .

A．No problem                                              B．Think nothing of it

C．Not at all                                                   D．It doesn’t matter

—I really don’t know how to thank you enough .

    — ________.

         A．No problem                B．Think nothing of it   

         C．Not at all                 D．It doesn’t matter 

—I really don’t know how to thank you enough .

—       .

A．No problem                           B．Think nothing of it

C．Not at all                           D．It doesn’t matter

— I really don’t know how to thank you enough.

— ________________.

A．No problem        B．Think nothing of it   C．Not at all          D．It doesn’t matter