Question

Чем отличается тема was were с had

Answer 1

Was и were-это глагол быть в разных склонениях
I-was
You-were
He/she/it-was
We-were
They-were

Answer 2

Was и were относятся к времени Past Continuous, а had к Past Perfect. Past Continиous используется,  когда "длилось в момент прошлого"( напр. шли), а  Past Perfect "закончилось к моменту или действию" (напр. ушли)