My mother often cooks delicious (美味的)food______ us.
If_____litters, our world will be more beautiful.
—Can the plane fly _____ the Atlantic Ocean?—Yes,but it needs to go_____the clouds for hours.
—Can you tell me _____when the teacher came into the classroom?—Sorry,I don’t know.
The teacher said that _____ of the boys would take part in the fashion show.
—______ did your sister leave China?—She______ for three years .