Past Perfect: an action finished before another action in the past
Regula de formare: had + vb - 3rd form (Past Participle)
Exemplu: 1) I HAD read the history lesson BEFORE I did Maths exercises.
2)I didn't recognize Mr. Mackenzie. He HAD CHANGED a lot.
3)They HAD LEFT before my arrival there.
4)Nobody HAD CLEANED the furniture for weeks.
5)A thief HAD STOLEN her fur coat.
time to use: when, before, after, by the time
