1I think a city should have commercial areas and residences separated.  2We should prioritize room for raising children.  3Space in a city is limited, so it should be maintained for parks and community use, so that children can play there.  4What is more, such a city would be safer for elderly people too.  5In busy cities, people have to watch out for many things, such as cars, bicycles, traffic lights and pedestrians.  6For these reasons, I think a city should have separate commercial and residential areas.