The professor advised us to think outside the box and to________ new, different, or unusual solutions．

1. A.
   put up with
2. B.
   come up with
3. C.
   keep up with
4. D.
   catch up with

The professor advised us to think outside the box and to________ new, different, or unusual solutions．

A．put up with             B．come up with  

C．keep up with    D．catch up with