According to Professor Johnson, we don't have to read the book if we don't want to, as it is optional.
根据约翰逊教授的说法，我们不想读这本书，就不必读，因为它是选读的。
The value for the OrderDate is set by calling the Bind expression and passing to it the name of the column in the GridView's associated data source and an optional data format string expression.
OrderDate的值是通过调用Bind表达式并向它传递GridView的关联数据源中列的名称和一个可选的数据格式字符串表达式来设置的。
Transforms is an optional ordered list of processing steps that were applied to the resource's content before it was digested.
Transforms是一种选择性的处理步骤排序清单，在摘录资源内容之前，对它应用这些步骤。
It is always optional to re-state any base interface in a partial class.
分布类中是否重新声明它所实现的接口也是可选的。
Note that this step is optional; if you do not include the component in the palette, it can still be added to places by dropping the portlet (Sametime Unyte Meeting) into the place.
注意这一步骤是可选的；如果没有在面板中包含组件，那么仍然可以通过将portlet（SametimeUnyteMeeting）放到位置中来完成添加。
It defines some semantics for how to treat headers such as whether processing of the header is optional.
它定义了一些关于如何处理消息头的语义，比如头的处理是不是可选的。
Its use is optional, meaning that a resource adapter is not required to implement it.
它的使用是可选的，这意味着资源适配器不一定非得实现它。
The submission rule is optional; you need it only if you want to submit just the data instance instead of the entire form.
提交规则是可选的；只有在希望提交数据实例而不是整个表单的情况下，才需要提交规则。
That is optional; the profile author does not have to import it.
这是一个可选项; 创建概要文件不用必须导入它。
You may find it helpful to use the debugger for your initial test, although this is optional.
您将发现，一开始使用调试器进行测试会有所帮助，虽然不是必须这样做。
Once you’ve signed up for this (and it is optional, at least for now) you don’t need to do anything else to “share” your activity with Facebook.
一旦你同意注册了这个功能（这是可选的；至少目前是），你想分享你的活动的时候，你不需要做任何事。
It is optional but useful to model partitions.
建模划分是可选的但是有用的。
For SOA to be successful, SOA business and technical governance is not optional, it is required.
对于SOA的成功，SOA业务和技术治理不是可选的，而是必须使用的手段。
If the optional start is specified, it indicates the character position in the source-string at which the search is to begin.
如果指定了可选的起始位置，则表明它是源字符串中开始进行搜索的字符位置。
If the package is serialized to XML, it will contain the optional elements that were recorded on load, as shown in Figure 5.
如果这个包被序列化为xml，它将包含在加载时记录的可选的元素，如图5所示。
Although this is optional, it is a good test to check that the system has been configured correctly.
虽然这是可选的，但是可以很好地检查系统是否配置正确。
As Listing 4 illustrates, when any arguments are optional, it is usually necessary to decide in advance the order in which they must be specified.
正如清单4所说明的，当任何参数可选时，通常需要事前决定其指定的排序。
In case a virtual shard id map is not provided (it is optional), it is defaulted to the physical shard id map.
如果未提供虚拟碎片ID映射(可选)，默认为物理碎片id映射。
Note that though this step is optional in deploying the ruleapp to rule Execution Server (RES), it is a recommended and more systematic approach to store the RES configuration for future use.
请注意，虽然此步骤在将ruleapp规则部署到ruleExecutionServer (RES)是可选的，但是存储RES配置以备将来使用是更有系统的方法，故推荐这样做。
It is worth mentioning that there are not optional components and that the following technologies must be implemented fully for a solution to conform with the Web profile.
值得注意的是，Web Profile并没有什么可选组件，要想实现符合Web Profile的解决方案就必须实现如下这些技术？
The CommentBlock function in Listing 4, for example, assumes that the comment introducer is the optional argument that is most likely to be needed, and so places it first in the parameter list.
例如，在清单4中的CommentBlock函数，假设评论人可能是最需要的可选参数，所以将其放置在参数列表的第一位。
However, it is also possible to declare any of them as optional by setting the 'required' attribute to 'false'.
然而，也可以将required属性值设置为false来声明它们中的任何一个。
This syntax is a little confusing at first, but it gives Ruby the ability to simulate named, optional parameters with minimal additional overhead to the language.
开始时，这个语法有点让人迷惑，但是它为Ruby提供了模拟已命名的可选参数的能力，而所需的语言的额外开支却很小。
It is an optional service that can be used to store session state data outside of the Web application memory space.
有一项可选服务可将会话状态数据保存在web应用程序内存之外。
For the Domino server, there is the optional feature to restart it after the diagnostic information has been collected.
对于Domino服务器，在收集诊断信息之后重新启动是可选特性。
The colon at the start of the command is optional, but it's a good idea to include it; doing so makes the command easier to locate in the (usually complex) argument list of an autocmd.
命令开始处的冒号是可选的，但是最好加上；这么做能够让命令更轻松地在一个(往往很复杂的)autocmd参数清单中定位。
I'm not planning to get it, because like you said, music is optional.
我不打算得到它，因为像你说的，音乐是可选的。
Although adherence to the aspirational standards is not easily measured, conducting ourselves in accordance with these is an expectation that we have of ourselves as professionals-it is not optional.
虽然符合共识性准则的标准不太容易衡量，但职业行为符合这些准则并不是可有可无的，而是作为专业人士所被期望遵循的。
Although adherence to the aspirational standards is not easily measured, conducting ourselves in accordance with these is an expectation that we have of ourselves as professionals-it is not optional.
虽然符合共识性准则的标准不太容易衡量，但职业行为符合这些准则并不是可有可无的，而是作为专业人士所被期望遵循的。
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