Tā búhuì shuō yíɡe zì.
他不会说一个字。
He would not say a word.
Notes:
他(tā): he
不会(búhuì): can't
说(shuō): to speak
一个(yíɡe): one
字(zì): word
Example:
A:他不会说一个字。
Tā búhuì shuō yíɡe zì.
He would not say a word.
B:他很坚强。
Tā hěn jiānqiánɡ.
He's a tough guy.