「言之成理 / 言之有理」

(pos:語句)
<explanation>
yue:講嘅嘢成道理而且令人信服
eng:to deliver a claim in a rational and convincing manner
<eg>
yue:佢講嘢言之成理，抵佢做大狀。 (keoi5 gong2 je5 jin4 zi1 sing4 lei5, dai2 keoi5 zou6 daai6 zong6.)
eng:His arguments are rational and sensible. No wonder he's such a good barrister.