Medium wavelength UVB rays can enter the skin's superficial layers and long length UVA rays can penetrate into the deeper layers.

中等波长的b波紫外线 可以进到皮肤的表层，而长波长的a波紫外线 则可进入皮肤的深层。

At the same time, a second skin layer called the pupal cuticle forms underneath the first.

同时，在第一层皮肤下面形成称为蛹角质层的第二层皮肤。

Paper can also leave fragments and chemicals behind that irritate your vulnerable inner skin layer, or dermis.

纸张还会留下碎片和化学物质，它们会刺激您脆弱的皮肤内层或真皮层。

This procedure has mostly been replaced by laser resurfacing, which uses laser pulses to remove skin layer by layer until the scar has smoothed out.

这种疗法基本上已经被激光疗法所取代了，激光疗法是用激光脉冲一层一层地除去皮肤细胞直到疤痕被消除。

Epidermal cells divide, move outwards, die, and form the skin's tough outer layer, which gradually sheds off in single cells far too small to see.

表皮细胞分裂、外移、凋亡，形成皮肤坚韧的屏障，并以肉眼无法看到的单细胞逐渐脱落。