tā / yī jǐn zhāng / shuō huà / jiù / yǒu xiē / kē ba / dàn / zhǔn bèi / de / hěn chōng fèn

他一紧张，说话就有些磕巴，但准备得很充分。

Whenever he gets nervous, he stammers a little when speaking, but he is very well prepared.