“Again and again” with 一再 and 再三
Both adverbs have the same meaning, but differ slightly in usage.
The adverbs 一再 
and 再三 denote the repetition of an action.
They both should be stated before the predicate, and they both may be followed by the particle 地 .
and 再三 denote the repetition of an action.
They both should be stated before the predicate, and they both may be followed by the particle 地 . Pay attention
We use 一再 when speaking about the repetition of actions in the past.
We use 再三 when speaking about the repetition of an action either in the past or in the future.
Examples
他再三感谢我
He thanked me again and again
tā zàisān gǎnxiè wǒ
我一再地警告他，但是他不听我的
I warned him over and over again, but he didn’t listen to me
wǒ yízài de jǐnggào tā, dànshì tā bù tīng wǒ de
明天我要再三强调这件事情
I want to emphasize this matter again and again tomorrow
míngtiān wǒ yào zàisān qiángdiào zhè jiàn shìqíng
After 再三, we can only state verbs with a positive or neutral meaning. These verbs should denote an action that the speaker performs himself and can control.
These restrictions to not apply to 一再.
Examples
自入队以来他一再受伤
He has been injured repeatedly since joining the team
zì rù duì yǐlái tā yízài shòushāng
你应再三考虑
You should think twice about that
nǐ yīng zàisān kǎolǜ
We should state 一再 only before a verb.
Sometimes we can state 再三 after a verb, but this is an exception.
Examples
我思考再三，决定不买这条裙子
I thought twice and decided not to buy this dress
wǒ sīkǎo zàisān, juédìng bù mǎi zhè tiáo qúnzi
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