这个阶段星云的大小与其质量成反比。The size of the nebula at this stage is inversely proportional to its mass.对暗星云的研究被一种新发现所推进.The investigation of dark nebulas has been facilitated by a new discovery.形成行星状星云的这一图象可能会引起许多异议.Many objections...
云仙山今天一直在向外喷涌火山灰、气体和火山岩。Mount Unzen has been spewing out volcanic ash, gas, and rock today.玄武岩是最普通的火山岩.Basalt is the commonest volcanic rock.火山岩在正常情况下有强的磁化率.Volanic rocks have high susceptibilities under normal conditions...