tā / xìng / gé / yū / nè / bù / shàn / yú / dāng / zhòng / biǎo / dá / zì / jǐ / de / xiǎng / fǎ

他性格迂讷，不善于当众表达自己的想法。

He is cautious and reserved by nature and is not good at expressing his ideas in public.