Questions & Answers about Het was dit boek dat is gepubliceerd.
Why do we use dat instead of die to connect the sentence here?
In cleft sentences, the connecting word depends on the noun you are emphasizing. Because boek is a het-word, we must use dat. If we were emphasizing a de-word, like de brief (the letter), we would use die: Het was deze brief die is gepubliceerd.
Why does the sentence use is gepubliceerd instead of heeft gepubliceerd?
This is the passive voice. The book didn't publish anything itself; it was published. In Dutch, the present perfect passive (has been published) is formed with the helping verb zijn (to be) rather than hebben (to have).
Why are both verbs (is and gepubliceerd) pushed to the very end?
The word dat introduces a subordinate clause. As a rule in Dutch, subordinate clauses push all their verbs to the end of the sentence.
Is it possible to flip the verbs and say dat gepubliceerd is?
Yes! At the end of a subordinate clause, the order of the helping verb (is) and the past participle (gepubliceerd) is flexible. Both dat is gepubliceerd and dat gepubliceerd is are perfectly correct and mean the exact same thing.