at one time and another的用法和样例：
- Even though the bottle is tightly stoppered, the scents will be evaporated after a long time.
- The umbrella holder must be good at singing traditional songs and composing new songs impromptu so that they can meet the demand in different places.
- Of course, many problems recur at various periods.
- She has devoted herself to an extensive variety of public subjects, at various time, and is at present devoted to the subject of Africa.