[单项选择]Before the 1500’s, the western plains of North America were dominated by farmers. One group, the Mandans, (31) in the upper Missouri River country, primarily in present-day North Dakota. They had large villages of houses (32) close together.
The (33) arrangement enabled the Mandans to protect themselves more easily (34) the attacks of others who might seek to (35) some of the food these highly capable farmers stored from one year to the next.
The women had primary responsibility for the fields. They had to exercise (36) skill to produce the desired results, (37) their northern location meant fleeting growing seasons. Winter often lingered; autumn could (38) by severe frost. For good measure, during the spring and summer, drought, heat, hail, grasshoppers, and other (39) might await the wary grower.
Under (40) conditions, Mandan women had to grow maize capable of weathering (41) They began (42