It covers all parts and labour, except for normal wear and tear of course.

它包含所有零件和人工服务，当然除了正常磨损和破损外。

These epithelial cells produce keratin, a protein that makes the layer tough, and protects against normal wear and tear from food and drinks.

这些上皮细胞产生角质，一种让这层结构变得坚硬的蛋白质，能保护黏膜免受饮食物的磨损。

Yanagisawa says he thinks his glass could fix tiny cracks in car or train windows caused by pebbles or normal wear and tear.

他说，他认为他的玻璃可以修缮汽车或火车的窗户由碎石引起的细小的裂缝或正常磨损。