彗星在圆形轨道上形成,但当它们冒险太接近行星时,就会被引力抛入现在的椭圆轨道。
Comets formed in circular orbits but were gravitationally flung into their present-day elliptical orbits when they ventured too close to planets.
它们可能接近圆形或者接近雪茄一样的瘦长形。
They may be nearly circular or so elongated that they take on a cigarlike appearance.
接近照片顶部尽头(即北部),冰雪变得较稀少,但是左上角一个巨大的撞击陨石坑壁却为环形山底的一块椭圆形积冰提供了庇护所。
Toward the top (northern) end of the image, the ice becomes sparser, but the walls of a large impact crater in the upper-left corner provide a refuge for an oblong ice deposit on the crater floor.
If I looked within the skin, one of the lower layers of your skin, the connective tissue layer, you'd find many fibroblasts there and they're just waiting in a more rounded shape than this, just waiting to do their job.
如果观察皮肤,更深处的一层细胞,结缔组织层,就能看到许多成纤维细胞,它们平时形状接近圆形,时刻准备着去完成自己的任务
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