at a time or at the time از كدام و كجا استفاده كنيم؟

‘At a time’ refers to now: اشاره به اكنون داره

At a time when there are so many people unemployed you have to take any job you can get. 

or the future. و يا اشاره به آينده

We could meet at a time that suits you. 

‘At the time’ refers to the past. اشاره به گذشته دارد

At the time I was young and foolish.