The colloquial phrase 那倒是
We use the phrase 那倒是 
to express agreement with what was said before.
We can state it either at the beginning of a sentence, at the beginning of the second clause of a sentence, or as its own sentence.
to express agreement with what was said before.
We can state it either at the beginning of a sentence, at the beginning of the second clause of a sentence, or as its own sentence. Pay attention
The phrase 那倒是 is used only in colloquial speech.
Examples
那倒是挺有趣的
Well, that's really interesting
nà dàoshi tǐng yǒuqù de
如果能找到失败的原因，那就非常好 —— 那倒是！
It would be very good if we could find the reason for the failure —— That’s true!
rúguǒ néng zhǎodào shībài de yuányīn, nà jiù fēicháng hǎo — nà dàoshi
现在看来，那倒是个很好的办法
It really seems like a good idea now
xiànzài kàn lái, nà dàoshi ge hěn hǎo de bànfǎ