The traditional houses in northern China are

23.( 1)A B (2) Reasons for the difference North: Farmland is mostly dry land, mainly planted with wheat and soybeans, harvested once a year or three times every two years. South China: The farmland is mostly paddy fields, mainly planted with rice and rape, and the water and heat conditions of two and three crops a year are different. North: Land transportation is the main mode, and cars and carriages are often used as means of transportation. South: Water transportation is still a common mode of transportation. It is dry in the north and there is more precipitation in the south. The roof slope of northern residential houses is small and the wall is thick. South: The roofs of residential houses are steep and the walls are high, with less precipitation in the north and more precipitation in the south. The temperature in the north is low and the south is hot and humid.