4 sentences

1. 他通过自学掌握了三门外语。

   tā tōng​guò zì​xué zhǎng​wò le sān mén wài​yǔ.

   He mastered three foreign languages through self-study.

   Source: Dong Chinese Dictionary

2. 他在闲暇时间喜欢自学钢琴。

   tā zài xián​xiá shí​jiān xǐ​huan zì​xué gāng​qín.

   He likes to teach himself piano in his spare time.

   Source: Dong Chinese Dictionary

3. 他没有受过正规教育，完全是自学成才。

   tā méi​yǒu shòu guo zhèng​guī jiào​yù, wán​quán shì zì​xué chéng​cái.

   He never received a formal education and is entirely self-taught.

   Source: Dong Chinese Dictionary

4. 他在努力工作，与此同时，他还在自学英语。

   tā zài nǔ​lì gōng​zuò, yǔ​cǐ​tóng​shí, tā hái zài zì​xué Yīng​yǔ.

   He is working hard; meanwhile, he is also teaching himself English.

   Source: Dong Chinese Dictionary