Я буду ставить 3 точки где над вставить глагол to be.
Professor ... here ten days ago. I ... in London last week. We at school yesterday.
He ... at the airport yesterday

Professor was here ten days ago. I was in London last week. We were at school yesterday.
He was at the airport yesterday

Professor was here ten days ago. I was in London last week. We were at school yesterday. He was at the airport yesterday. Профессор был здесь десять дней назад. Я был (была) в Лондоне на прошлой неделе. Мы вчера были в школе. Он был в аэропорте вчера.