(+) Onderwerp + had + voltooid deelwoordI had already done my homework when the teacher explained the rules.
(?) Had + onderwerp + voltooid deelwoord
Had she called you before you went on holiday?
(-) Onderwerp + had not + voltooid deelwoord
She had not finished her homework yet when the bell rang.
Voltooid deelwoord = 3e rijtje / ww+ed