in a while的用法和樣例：
例句
- She looked in on us [at our office]once in a while.
每隔些時候，她都到我們這兒[辦公室]來一趟。 - Once in a while he goes with us to the movies on Saturday night.
偶爾在星期六晚上他同我們一道去看電影。 - Once in a while we go to a restaurant but usually we eat at home.
我們偶爾下館子--但一般都在家吃。 - While reading he looked out of the window once in a while.
他正在讀書，有時還朝窗外看看。
