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.

youdao

各个方面以某种方式合并到常规原始程序码中并产生原始程序码的中间版本，然后将该中间版本编译成可执行格式。

Aspects are in some way merged into the regular source code and produce an intermediate version of the source code that will then be compiled to an executable format.

youdao