A、There were some pages missing in the old books. B、Some old books could not be found in the museum. C、Some pages were broken in

W: Excuse me, I’ve been using this old book for a research project and (8)I notice that a lot of pages are turning brown and becoming brittle.
M: Yes. Unfortunately, that’s a common problem with books made from wood pulp.
W:(9)I suppose that to make paper from wood, you have to add a lot of chemicals and acids to make it turn white.
M: Exactly, and it’s the acid that eventually eats away the paper.
W: Oh, that actually makes sense, but this book’s not even 75 years old and I’ve seen books in museum that are hundreds of years old and they’re in free condition.
M: Well, you see, (10)books have been made from wood pulp only since the 1850s, before that they were mostly made from materials like animals’ skins, and no chemicals were added.
W: It’s a shame that those older wood pulp books are going to fall apart someday. Is there anything that can be done to preserve them?
M: (11)En, currently the only way to stop the books from decaying is to remove the binding and treat each page individually to remove the acid.
W: That doesn’t sound very economical.
M: No, it isn’t. It’s not practical to treat a large number of books with this process, so we only try to rescue the most valuable edition books in our collection.
W: Well, thanks for the explanation. I’d better get back to my project.
M: Good luck and I hope the old book will hold long enough for you to finish it.
Questions 8 to 11 are based on the conversation you have just heard.
8.What problem did the woman find?
9.How to make paper from wood according to the woman?
10.What were books made from before the 1850s?
11.How to preserve those old books according to the man?