—How do they go to school?
—They go to school ______foot.
A．at B．in C．on
We see some people ____ happily on the street.
A. walking B. to walk C. walks
_______ you feel tired?
A. Are B. Do C. Does
There _______ many people on the street.
A. is B. are C. have
May I ____ some grapes?
A. to have B. having C. have
Danny is singing a song ____ my mother.
A. to B. for C. across