3 sentences

1. 在先秦时期，大夫是地位很高的官员。

   zài xiān Qín shí​qī, dà​fū shì dì​wèi hěn gāo de guān​yuán.

   During the pre-Qin period, 'Dafu' was a high-ranking official title.

   Source: Dong Chinese Dictionary

2. 他在课上专门讲解了先秦时期的小说家。

   tā zài kè shàng zhuān​mén jiǎng​jiě le xiān Qín shí​qī de Xiǎo​shuō​jiā.

   In class, he gave a special lecture on the novelists of the Pre-Qin period.

   Source: Dong Chinese Dictionary

3. 教授正在台上讲解先秦农家提倡的生产方式。

   jiào​shòu zhèng​zài tái shàng jiǎng​jiě xiān Qín Nóng​jiā tí​chàng de shēng​chǎn fāng​shì.

   The professor is on stage explaining the production methods advocated by the pre-Qin School of Agronomists.

   Source: Dong Chinese Dictionary