根据句意及汉语提示填空.
小题1:__________ __________the answer can help you understand the passage.( 找出)
小题2:The car slowed down in time and _________ _________ into the wall. (避免撞击)
小题3:He _________ _________his son once a week.(收到……来信)
小题4:They _________ _________those problems by themselves at last. (处理)
小题5:It’s _______ ________to clean the classroom.(轮到我们)