I bet Mrs. Black will come to help us with the celebration if she ______ too busy tomorrow.

A．is          B．will be          C．won’t be            D．isn’t

I bet Mrs. Black will come to help us with the celebration if she ______ too busy

tomorrow.

       A. is                         B. will be                  C. won’t be               D. isn’t

I bet Mrs．Black will come to help us with the celebration if she ________ too busy tomorrow．

1. A.
   is
2. B.
   will be
3. C.
   won’t be
4. D.
   isn’t