Questions & Answers about Я забыл название этой книги.
The lesson is about nouns ending in -ии, so why does название end in -е here?
The current lesson teaches the Prepositional case, which is used after certain prepositions (like talking 'about a title' - о названии). In this sentence, however, название is the direct object of the verb забыл (forgot), so it must be in the Accusative case. For neuter nouns, the Accusative is identical to the dictionary (Nominative) form, which simply ends in -е.
Why is the phrase этой книги used instead of эта книга?
этой книги is in the Genitive case, which often acts like the English word 'of'. Because we are saying 'the title OF this book', both the demonstrative pronoun (эта becomes этой) and the noun (книга becomes книги) take the Genitive endings.
Could I use имя instead of название to say 'the name of the book'?
No, in Russian, имя is reserved for the names of people and pets. For the names or titles of inanimate objects like books, movies, restaurants, or companies, you must always use название.
Why use the perfective verb забыл instead of the imperfective забывал?
You use the perfective забыл because forgetting the title is a single, completed action that has a direct result in the present (you currently do not know the title). The imperfective забывал would mean you used to forget it repeatedly in the past, or were in the process of forgetting it.