a pack of cards的用法和样例：
- Mary took a pack of cards from the drawer and we all sat down to play.
- A pack of cards has been spread on the table.
- People who tell your future by means of a pack of cards are frauds.
- The performer has a pack of cards and gave a second pack to a spectator.
- He used to smoke a pack of cigarette a day.
- Can you lend us a pack of playing cards?