past perfect · "had" · Past · Level B
A past before another past. By the time one thing happened, another had already happened. You build it with había plus the -ado / -ido form of the verb.
Examples
Ya había comido cuando llegaste.
I had already eaten when you arrived.
Nunca había tenido que esperar tanto.
I had never had to wait so long.
Careful
Slot 2 is the only slot that needs another past event to make sense. If there is no 'when' in the sentence, you probably want 1a.
On the site
The builder puts the helper había in 1b and adds the -ado / -ido form: tengo que becomes había tenido que.
Practice 2 in Build