2 sentences

1. 春秋更替，岁月流转。

   chūn​qiū gēng​tì, suì​yuè liú​zhuǎn.

   Seasons alternate and time flows on.

   Source: Dong Chinese Dictionary

2. 自然界的发展是一个不断代谢、更替的过程。

   zì​rán​jiè de fā​zhǎn shì yī gè bù​duàn dài​xiè, gēng​tì de guò​chéng.

   The development of nature is a process of constant metabolism and replacement.

   Source: Dong Chinese Dictionary