Why is marking up a book indispensable to reading?

为什么在阅读过程中在书上做标记是必不可少的呢？

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That done, XHTML 2.0 seeks to address the problems of HTML as a language for marking up Web pages.

这项任务完成了，XHTML 2.0致力于解决HTML作为一种Web页面标记语言的问题。

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You should also understand all of the advantages that MathML 3.0 will soon bring for marking up mathematics in XML.

也应该了解MathML 3.0很快将为在XML中标记数学表达式带来的所有优势。

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The president meets Wednesday with Senate Democrats, as the budget committee there and in the House of Representatives begin "marking up" budget resolutions, which form the framework for appropriations and other important legislation.

VOA: standard.2009.03.24

He was motionless, all but for one finger that moved up and down in front of his face as if he were marking time with it.

他一动也不动，除了一根手指在他的面前上下摆动,好像在用它标记时间。

耶鲁公开课 - 1945年后的美国小说课程节选

The market voted its approval by marking up Panenergy's stock fivefold over five years.

FORBES: Trading places

The market had voted its approval by marking up Panenergy's stock fivefold over five years.

FORBES: Trading Places

Mr. Schmitz tends to use his slender-nibbed fountain pens for tasks like marking up a spreadsheet.

WSJ: Jan-Patrick Schmitz of Montblanc on Choosing the Right Pen