A midday rest ______ recover brain power to its best and make people perform better．

       A．can             B．must                 C．need                   D．shall

–Do you think Professor Smith_________be in the lab?

--I’m not sure.

Don’t feel guilty about it. Anyone         make mistakes in their life.

       A．must                  B．can                     C．shall                   D．need

     we go to the McDonald’s? I’m sick of the food there!

A．Need             B．Can              C．Shall             D．Must