planet-formingCOCA²³⁹⁵⁷⁵BNC¹⁷³⁹⁹⁵⁺² 例句 Although the stars were just half a million years old—still in their infancy in stellar time scales—most had already lost their planet-forming disks of gas and dust. 虽然这些恒星只有五十万年——按照恒星的时间尺度计算，它们还处于婴儿期——但是大都已经失去了其形成行星的由气体与尘埃组成的圆盘。 yeeyan