xiǎng jiē biéren de huà, kěyǐ shuō 'wǒ bǔchōng yīdiǎn' huò 'wǒ jiēzhe zhège diǎn shuō'

想接别人的话，可以说“我补充一点”或“我接着这个点说”。

If you want to join in on someone else's point, you can say 'I'd like to add something' or 'I'll continue from this point'.