再三(zài sān) or means "repeatedly" or "time and again", and can be placed before or after a verb.
Basic Structure
再三 is interesting because it can be placed before or after the verb!
再三 + verb
verb + 再三
Examples
lǎoshī xiànɡ tā zàisān qiánɡdiào “wàiɡuó” bú shì yī ɡè ɡuójiā。
老师 向 他 再三 强调 “外国” 不 是 一 个 国家。
The teacher has stressed to him over and over that "foreign" is not a country.
zhōnɡɡuó zhènɡfǔ zàisān jǐnɡɡào měiɡuó búyào ɡānshè zhōnɡɡuó de nèizhènɡ。
中国 政府 再三 警告 美国 不要 干涉 中国 的 内政。
China's government warns America repeatedly not to interfere in China's affairs.
tā zàisān yóuyù zhīhòu,zhōnɡyú xuǎnzé zhuāzhù shíjī!
她 再三 犹豫 之后,终于 选择 抓住 时机!
After hesitating again and again, she finally decided to seize the opportunity.
一再 can also be used to convey the same meaning but can only be placed before the verb:
xiǎowánɡ yízài chídào.
小王 一再 迟到。
Little Wang comes late repeatedly.
tā yízài bàoyuàn tā yùnqi hěnchà.
他 一再 抱怨 他 运气 很差。
He complains again and again about his bad luck.