Question 17 is based on the passage you have just heard.

     Most American college students need to be efficient readers. This is necessary because full-time students probably have to read several hundred pages every week. They don't have time to read a chapter three or four times. (16) They need to extract as much information as possible from the first or second reading.

    An extraordinarily important study skill is knowing how to mark a book. Students mark the main ideas and important details with a pen or pencil, yellow or blue or orange. Some students mark new vocabulary in a different color. Most students write questions or short notes in the margins. Marking a book is a useful skill, but it's important to do it right. First, read a chapter with one pen in your hand and others next to you on the desk. Second, read a whole paragraph before you mark anything. Don't mark too much. Usually you will mark about 10% of a passage. (17) Third, decide on your own system for marking. For example, maybe you will mark main ideas in yellow, important details in blue and new words in orange. Maybe you will put question marks in the margin when you don't understand something and before an exam. Instead, (18) you just need to review your marks and you can save a lot of time.

(17). What suggestion does the speaker give about marking a textbook?

解析：细节理解题。根据文章可知，讲话者对如何做标记提出了三条建议：一、读书时，手里拿着一支笔，桌上放着一支笔；二、读完一整章再做标记；三、建立自己的标记系统。A选项与第三条建议“建立自己的标记系统”一致，因此选择A项。