rolling
adjective [ before noun ] uk/ˈrəʊ.lɪŋ/ us/ˈroʊ.lɪŋ/
(GRADUAL)
逐渐的;逐步的
gradual
The plan is for a rolling extension of the tax over the next ten years. 计划是在未来十年中将这一税种的征收范围逐步扩大。
(OF HILLS)
（山峦）平缓起伏的
(of hills) gently rising and falling
The train journey took us through a valley past rolling hills. 我们乘坐火车沿一条山谷穿过绵延起伏的山峦。
Idiom
a rolling stone (gathers no moss)idiom old-fashioned saying 滚石不生苔，来去真自在（表示经常在外游荡或老换工作的人可以不用担负责任，但是也居无定所）
said to mean that a person who is always travelling and changing jobs has the advantage of having no responsibilities, but also has disadvantages such as having no permanent place to live
Hal was a bit of a rolling stone before he married and settled down. 哈尔以前生活有些漂泊不定，直到婚后才安顿下来。