Is this OK, There are some open books of 90 degree?
I mean these books are open and the angles of them are all 90 degree. How do I say it naturally?
Thanks!
No. I'm not even sure I understand what you mean. Nobody would describe an open book by saying the pages were at 90 degrees. I'm trying to picture in my mind what you want to describe but I'm still having difficulties.
Do you mean the books look like this?
http://www.openbookpublishers.com/shopimages/sections/normal/Open-Bookpic.jpg