every once in a while的用法和样例：
- We go out for a walk once in a while.
- He would spend hours in the bathroom or on the telephone.
- A knitter has to be a twister occasionally.
- We go for walks in the fields occasionally.
- He was often in jeopardy of his life.
- The castle is said to be haunted by a phantom.
- Diligence is often a ladder to success.
- Churches are often built in the form of a cross.