Questions & Answers about Bardzo długo czytałam tę książkę.
How do we know the speaker of this sentence is female?
Look at the verb czytałam. In the Polish past tense, singular verbs change based on the gender of the speaker. The -łam ending is used for women. If a man were speaking, he would use the masculine ending and say czytałem.
Why is there no Polish word for 'I' in this sentence?
Why does 'this book' change to tę książkę instead of staying as ta książka?
Because the book is the direct object being read, it takes the accusative case. For feminine nouns and pronouns in this case, the -a endings change to -ę. That is why ta książka becomes tę książkę.