图4显示了dnt字符串的一个例子，以及一种很好的关键字表达方式，这种方式将单词组合成字符串，中间不留空格(例如WebSite通常是关键字)。
Figure 4 shows you an example of DNT strings and a good practice of keyword expression because the strings combined without Spaces between words such as WebSite are usually keywords.
直到现在，表达消息条件事实上还没有一个一致的方法，以便们可以应用于中间件层。
Until recently, there really has never been a single consistent way of expressing message conditions so that they can be applied on the middleware layer.
没有表达式树的话，我们是不可能用描述格式来表示一个表达式的。他们唯一的表示方式是IL(中间语言)，这种语言对于重新表述用户的意图来说太低层次了。
Without expression trees, its impossible to describe expressions in a descriptive format; the only description of them is IL, which is too low level to re-create the user's intent for the expression.
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