一再 + Verb (again and again)

"Again and again" (formal)

• repeatedly一再yī zài + Verb = "again and again / repeatedly / time after time".
• he / him他tā一再强调yī zài qiáng diàosafe安全ān quán = "he repeatedly stressed safety."
• A formal cousin of over and over again再三zài sān, common in writing.

Subj + repeatedly一再yī zài + Verb

• repeatedly一再yī zài marks an action insisted on, over and over.

he他tārepeatedly一再yí zàistress强调qiáng diàosafety安全ān quán。

• 一再强调yī zài qiáng diàosafe安全ān quán = "repeatedly stressed safety."

Recap

Read the full reference: HSK 6 grammar — Adverbs.