2 sentences

1. 每一件事物都有其内在的发展规律。

   měi yī jiàn shì​wù dōu yǒu qí nèi​zài de fā​zhǎn guī​lǜ.

   Every thing has its own inherent laws of development.

   Source: Dong Chinese Dictionary

2. 皮肤的弹性主要来自于其内部的胶原。

   pí​fū de tán​xìng zhǔ​yào lái​zì​yú qí nèi​bù de jiāo​yuán.

   The elasticity of skin primarily comes from the collagen within it.

   Source: Dong Chinese Dictionary