Unable to save sentences in PDF files to Word History

Hi River!
When a word is selected in a PDF file opened in Edge, the word is saved in Word History, but not the contextual sentence.
Since e-books are a great source for learning a new language, and most e-books are in PDF and ePub formats, allowing sentences of selected words in PDF and ePub files to be automatically saved in Word History and exported to Anki would be really useful.
Thanks a lot!