Spring defines a coherent data access exception class hierarchy (Figure 12) that you can use as a basis for your service- and DAO-layer exceptions.

Spring 定义了一致的数据访问异常类层次结构（请参见图 12），您可以将其用作服务和 DAO 层异常的基础。

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This layer is the basis of the system, but also the core elements of the training and education system.

该层是体系的基础，也是培训教育体系的核心要素。

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Secondly, we introduce the principle of telecommunication management network (TMN); explain the basis concept, function architecture, management layer and its application.

其次介绍了电信管理网(TMN)的基本原理，详细说明了TMN的基本概念、功能体系结构、管理分层结构以及TMN的应用。

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Delta spokesman Anthony Black said even with the runway closure long tarmac delays on a day-to-day basis are unlikely at JFK, but bad weather adds an unpredictable layer of complication.

CNN: Air traffic jams in New York likely to jump