( 1)②③①
(2) the terrain is flat; Dense population and large food demand; Rich in labor resources; Rain and heat in the same period; Planting has a long history.
(3) Northwest and Northeast America, Canada, Argentina, Russia, Ukraine and other countries.
(4) The Central Plains of the United States has a large production scale, a high level of mechanization and a high commodity rate.
(5) The terrain is flat and broad, the soil is deep, the fertilizer and water are abundant, the climate is mild, there is more precipitation, and the rain and heat are the same.
(6)②④
(1) According to the graphic positions of A, B and C, A is a commodity grain agricultural area, B is a monsoon rice agricultural area, and C is a mixed agricultural area.
(2)B is a monsoon paddy field agricultural area, where the advantages of developing monsoon paddy field agriculture are obvious, mainly manifested in superior natural conditions, large population and people's preference for rice.
(3) As A is a commodity grain agriculture, this agricultural geographical type is mainly distributed in the northeast and northwest regions with a vast territory and a sparsely populated area; Similarly, countries that develop this kind of agricultural production should also have the conditions of vast territory and sparsely populated.
(4) As can be seen from the picture, A is the central plain of the United States, where agriculture has the characteristics of large production scale, high commodity rate and high mechanization level.
(5) The natural conditions for developing commodity grain agriculture in the United States are superior, mainly including flat terrain, fertile soil, abundant water, suitable climate, simultaneous rain and heat, etc.
(6) Developed industries and advanced science and technology in the United States provide mechanical and technical support for agriculture.