Let's make the goal more complex and add some conditional text rendering - for example, CSS class names for even and odd table rows.
现在让我们实现更复杂的目标并添加一些有条件的文本呈现—例如，命名偶数和奇数表行的css类。
A preprocessing step performs macro substitution on program text, inclusion of other source files, and conditional compilation.
编译的预处理阶段对程序文本进行宏替换，包含进其他源文件，并进行条件编译。
You can also use conditional formatting in Excel to turn lines red if they meet certain criteria, then notice the pattern of red flecks in the gray lines of text, as you scroll.
你也可以用Excel里的条件格式满足某些条件的行的文字变成红色，然后在滚动文本时，注意观察红色行闪烁于灰色行之间的情形。
You can also use conditional formatting in Excel to turn lines red if they meet certain criteria, then notice the pattern of red flecks in the gray lines of text, as you scroll.
你也可以用Excel里的条件格式满足某些条件的行的文字变成红色，然后在滚动文本时，注意观察红色行闪烁于灰色行之间的情形。
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