Join point is an abstract notion; one does not actively define a join point.

连接点是个抽象的概念；不用主动定义一个连接点。

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The cloud is an abstract notion of a loosely connected group of computers working together to perform some task or service that appears as if it is being fulfilled by a single entity.

云是一个抽象的概念，表示松散连接在一起的计算机组，这些计算机共同执行某项任务或者服务，就像是使用一个单独的实体完成一样。

youdao

The key to Joda's internals — and at the heart of its design — is the chronology (the notion of which is captured by an abstract class of the same name).

Joda 本质 — 以及其设计核心 — 的关键就是年表（它的含义由一个同名抽象类捕捉）。

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