你说的话很有道理，我同意。

nǐ shuō de huà hěn yǒu dàolǐ, wǒ tóngyì.

What you said makes a lot of sense; I agree.

跟他讲道理没有用，他根本不听。

gēn tā jiǎng dàolǐ méiyǒu yòng, tā gēnběn bù tīng.

There's no use reasoning with him; he doesn't listen at all.

这个道理很简单，小孩子都能明白。

zhège dàolǐ hěn jiǎndān, xiǎo háizi dōu néng míngbai.

This principle is very simple; even a child can understand it.