Thanks for your reply
I have an idea after reading your reply...

If I need to read a whole book...
first time PRing , the goal may be..
I want to realize the context to help me solve the related problem in the text and related exam.

There may be 10 chapter in the book, each chapter may have two or more topics,
The second time , reduce the mass of reading to to chapter or even less. Thus the goal may become "I want to know the [TOPIC] such that I can solve the problem in the end of the chapter"

Do PRing five times to complete the whole 10 chapters.

I think it's a good idea to PRing the whole book as the first time reading and then decomposite the context into more sub-context then PRing partly .

Do you agree this ??