A contravariant delegate can be assigned another delegate of the same type, but with a less derived generic type parameter.

可以向逆变委托分配同一类型的其他委托，但需使用派生程度较小的泛型类型参数。

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An interface that has a contravariant type parameter allows its methods to accept arguments of less derived types than those specified by the interface type parameter.

如果接口具有逆变类型形参，则允许其方法接受与接口类型形参指定的派生类型相比，派生程度更小的类型的实参。

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That's what interface inheritance means; if you fulfill the contract of the more derived type then you are required to also fulfill the contract of the less derived type.

接口继承就是这样的；如果你要满足派生程度较高的类型的契约的话，你就必须要满足派生程度较低的类型。

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Diesel derived from coffee is less thick and can usually be burned in an engine with little or no tinkering.

ECONOMIST: Monitor

However, most policymakers agree that the industry must move beyond corn ethanol, which is less efficient than the sugar-derived stuff and pushes food prices upwards.

ECONOMIST: A dysfunctional system may become more so

Stem cells derived from umbilical cords are less versatile than embryonic stem cells, which could conceivably replace any cell in the body.

FORBES: Small Stem Cells Find Big Backers