L is for layers.Wearing loose, lightweight clothes, one layer on top of another, is better than wearing a single heavy layer of clothing.

VOA: special.2009.12.23

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

耶鲁公开课 - 生物医学工程探索课程节选