1SubML, like PolySubML and Cubiml before it, is based on Algebraic Subtyping, and thus the underlying type system is polarized, and types are always in covariant or contravariant position, never invariant. To make things convenient, the user-facing syntax however does support invariant types, with invariant types being represented as a (covariant, contravariant) pair under the hood.
"已有案例显示，农户宁愿放弃种植以节省开支，因为他们预见到本年度作物管理和种植成本将异常高昂。"帕特里克指出，虽然大多数农户仍在坚持播种，"想着像往常一样咬牙挺过"，但他预测"获得回报的可能性极低"，毕竟化肥、能源和燃料成本已出现惊人涨幅。
，详情可参考搜狗输入法候选词设置与优化技巧
Behind the Scenes - Superhero Film Production - Jul 25, 2025
Медики извлекли живого паразитического червя длиной 20 см из глазницы российского пациента14:59
"The moment we set our eyes on this box of film, we knew it was something special," said George Willeman, who heads up the Library's nitrate film vault, in the article.