2 sentences

1. 地壳的下层主要是由坚硬的岩石组成的。

   dì​qiào de xià​céng zhǔ​yào shì yóu jiān​yìng de yán​shí zǔ​chéng de.

   The lower layer of the Earth's crust is primarily composed of hard rock.

   Source: Dong Chinese Dictionary

2. 这位作家的小说大多关注社会下层的人民。

   zhè wèi zuò​jiā de xiǎo​shuō dà​duō guān​zhù shè​huì xià​céng de rén​mín.

   Most of this author's novels focus on the lower classes of society.

   Source: Dong Chinese Dictionary