This can include both constraints in general (for instance, not knowing what makes a good constraint), as well as a lack of knowledge regarding how to implement a constraint in a model.

这包含通常的约束(举例来说，不知道什么能形成好的约束)，和缺乏了解如何在模型中实现约束。

youdao

Objects have no inherent constraints, so explicit coding is required to implement the data validation.

对象没有固有的约束，因此要实现数据验证，必须进行显式编码。

youdao

Considering only pure business requirements is likely to result in service definitions that are impractical or impossible to implement, given the constraints of existing systems.

已知现有系统的约束条件，只考虑纯粹的业务需求很可能产生不实际或不可能实现的服务定义。

youdao

It is the ability to manage effectively and implement policy under a unique set of political, economic and social constraints that truly determines a leaders success, not a resume.

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"Even when there are no financial constraints, if these drugs are freely available, it is very, very difficult to actually implement the programme, " said Donald de Korte, a former head of US drugs firm Merck in South Africa who is running a pilot scheme.

BBC: Africa's Aids drugs debate heats up