
I had been working in the garden, when she came. - Я работал в саду, когда она пришла.
had + been + Ving
Примеры:They had been playing football for hours when it started to rain. - Они играли в футбол часами, когда начался дождь.
You had been waiting for me for hours untill I finally arrived. - Ты ждал меня часами, когда я наконец приехал.
had + not + been + Ving
We hadn't been working for 4 hours when they came. - Мы не работали 4 часа, когда они пришли.
He hadn't been watching the show untill we came. - Он не смотрел программу, пока мы не пришли.
В вопросительной форме had встает на первое место в предложении:Had + подлежащее + been + Ving?
Had you been studying Russian before you moved to Moscow? - Ты изучал русский язык, прежде чем переехал в Москву?
Had you been living here for a long time before you sold a flat? - Ты жила здесь долгое время пока не продала квартиру?

Had you been working? - Yes, I had. / No, I hadn't.
Had she been studying? - Yes, she had. / No, she hadn't.