Colorful Ideas

I/You/They/We/She/He/It  had been waiting.......

The past perfect continuous tense is like the past perfect tense, but it emphasizes the duration of an activity that was in progress before another activity or time in the past.

i.e.
1. Elma started waiting at 7am. Amin arrived at 9am. When Amin arrived, Elma had been waiting for two hours.
2. Amin finally came at nine o'clock. Elma had been waiting for him since seven.
3. The police had been looking for the criminals for two years before they caught him.