I didn’t quite follow him because he explained the theory _____that is too abstract for me.
When the invader arrived, millions of people ___ from their homeland.
After the war, a new school building was put up _____ there had once been a theatre.
_____, Mother will wait for him to have dinner together.
He will come to call on you the moment he ____ his painting.
____ difficult the task may be, we will try our best to complete it in time.