Every 10 years I buy а house. - Каждые 10 лет я покупаю дом. - Present Simple.
I am buying a house now. -Я сейчас покупаю дом. - Present Continuous
I have already bought a house- Я уже купил дом. - Present Perfect.
I was buying a house yesterday at 3 p.m. - Вчера в 3 часа я покупал дом. - Past Continuous
Yesterday by 3 p.m. I had bought a house. - Вчера к 3 часам я купил дом. - Past Perfect
I shall (или will) buy a house in 2 weeks. - Через 2 недели я куплю дом. - Future Simple
I will be buying a house tomorrow at 3 p.m. - Завтра в 3 часа я буду покупать дом. - Future Continuous
I will have bought a house tomorrow by 3 p.m.- Завтра к 3 часам я куплю дом. - Future Perfect Continuous