zài / zhè cì / gōng yì / huó dòng / zhōng / Lǐ / lǎo shī / yī mǎ dāng xiān / dài lǐng / dà jiā / qīng lǐ / hé àn

在这次公益活动中，李老师一马当先，带领大家清理河岸。

During this public service event, Teacher Li took the lead and guided everyone in cleaning up the riverbank.