2 sentences

1. 学生们正在教室里认真地听课。

   xué​sheng men zhèng​zài jiào​shì lǐ rèn​zhēn de tīng​kè.

   The students are listening attentively to the lecture in the classroom.

   Source: Dong Chinese Dictionary

2. 他今天听课时心不在焉，总是在看窗外。

   tā jīn​tiān tīng​kè shí xīn​bù​zài​yān, zǒng​shì zài kàn chuāng wài.

   He was absent-minded during the lecture today, always looking out the window.

   Source: Dong Chinese Dictionary