Professor Su, with a slip of paper in hand, was wondering where to find the address when all of a sudden he heard a child crying out randomly from an upstairs window of the opposite building, like a singer practising his voice:

• 苏林教授手持纸条，不知从何处找起，忽然听见对屋的楼窗上，有一个孩子有事没事地张口叫着：