滚动缓冲区

例句：

1. 1. The carwas rolling down the hill when I sawit.
   当我看到那辆车时，它正沿着山坡滚动。
2. 2. She rolled her eyesat him and walked away.
   她对他翻了个白眼然后走开了。
3. 3. Rollup your sleeves andget ready to work.
   卷起袖子准备工作吧。