6 sentences

1. 天气一下子变冷了。

   tiān​qì yī​xià​zi biàn lěng le.

   The weather turned cold all of a sudden.

   Source: Dong Chinese Dictionary

2. ‎你突然一下子就意识到这点了？

   ‎ nǐ tū​rán yī​xià​zi jiù yì​shí dào zhèi diǎn le?

   You just realized that all of a sudden?

   Source: OpenSubtitles

3. 经他一解释，我心里一下子明亮了。

   jīng tā yī jiě​shì, wǒ xīn​li yī​xià​zi míng​liàng le.

   After his explanation, everything suddenly became clear to me.

   Source: Dong Chinese Dictionary

4. 他的开场白很幽默，一下子就吸引了全场观众。

   tā de kāi​chǎng​bái hěn yōu​mò, yī​xià​zi jiù xī​yǐn le quán chǎng guān​zhòng.

   His opening remarks were very humorous and immediately captivated the entire audience.

   Source: Dong Chinese Dictionary

5. 他一下子就把作业做完了。

   tā yī​xià​zi jiù bǎ zuò​yè zuò​wán le.

   He finished his homework in no time.

   Source: Dong Chinese Dictionary

6. 他一下子钻进人群中不见了。

   tā yī​xià​zi zuān​jìn rén​qún zhōng bù​jiàn le.

   He suddenly dove into the crowd and disappeared.

   Source: Dong Chinese Dictionary