developed grain

例句：

1. 1. The farmers are busy developing new varieties of developed grain.
   农民们忙于开发新的成熟谷物品种。
2. 2. The government has introduced a policy to promote the development of developed grain.
   政府推出了一项政策来促进成熟谷物的发展。
3. 3. The developed grain is a source of energy and nutrition for many people.
   成熟的谷物是许多人的能量和营养来源。