It is acceptable, though not required, to remove unwanted keys from copies of the sets above.
从上述的集合副本中删除不必要的键，是可接受的，但并不是必需的。
Implementing an EJB tier, though not required, lays the foundation for creating a highly scalable, distributed application architecture.
虽然没有要求实现ejb层，但这样做可以为建立高度可伸缩的分布式应用程序架构提供基础。
The servlet filter USES log4j to log some information during processing and it is recommended, though not required, to enable the logging.
servlet筛选器在处理期间使用log4j记录一些信息，建议启用日志记录(但不是必需的)。
XForms implementations are allowed (though not required) to take advantage of knowledge about the expected type of the data to present a different widget for the same control.
XForms实现允许（尽管不要求）利用预期数据类型的信息以不同部件表示同一个控件。
XForms implementations are allowed (though not required) to take advantage of knowledge about the expected type of the data to present a different widget for the same control.
XForms实现允许（尽管不要求）利用预期数据类型的信息以不同部件表示同一个控件。
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