Learning XPath Expressions By Examples

Select all the preceding sibling before the chapter with a title named "XPath"

/book/chapter/title[text()="XPath"]/../preceding-sibling::*

Select all the paragraphs for which there exists a chapter title named "Stylesheet Basics"

/book/chapter/para[preceding-sibling::title='Stylesheet Basics']

Get the first <para> element in the book

(book/chapter//para)[1]