Out in front, Clarke had built up such a sizeable safety margin that he eased the pace and started cruising.克拉克远远地开在前面，已保持了一段足够长的安全距离，于是放慢了速度，开始巡航。He managed to knuckle down to his lessons long enough to pass his examination.他在离考试还有足够长时间的时候就开始认真学习，从而通过了考试。