"My new book was presented yesterday."
Translation:Mijn nieuwe boek werd gisteren gepresenteerd.
after possessive adjectives -mijn,haar,zijn- an "e" ending is attached to the adjective preceding the noun. whether it is a "het" or 'de" word does not make a difference. if you do not agree with me then type in : "haar nieuwe boek" in google and see the results for yourself.