3 sentences

1. 你每个晚上和周末都在做义工？

   nǐ měi gè wǎn​shang hé zhōu​mò dōu zài zuò yì​gōng?

   You volunteer every night and every weekend?

   Source: OpenSubtitles

2. 伊丽莎白在周末经常去孤儿院做义工。

   Yī​lì​shā​bái zài zhōu​mò jīng​cháng qù gū'ér​yuàn zuò yì​gōng.

   Elizabeth often volunteers at the orphanage on weekends.

   Source: Dong Chinese Dictionary

3. 你在这边做义工多久了？

   nǐ zài zhè​biān zuò yì​gōng duō​jiǔ le?

   How long have you been volunteering here?

   Source: OpenSubtitles