a fifty-cent piece的用法和样例：
- A fifty cent postage stamp was put on the heavy letter.
- A fifty cent postage stamp was put onthe heavy letter.
- Please break this into all fifty cent coins.
- You have a fifty to fifty chance to win the game.
- The 4 cent piece in the lot 4162 is chop cancelled.
- You have a fifty - fifty chance of winning.