The Chinese translation the vocabulary should be: "1，默不作声。2，保持沉默。"

很清楚。谢谢。

是的

we generally prefer to use 默不作声 ratherthan 默不吭声. it's a idiom that means hold one's tongue; keep silence; keep quiet [silent]; keep a calm sough; keep mum; refrain from comment; abstain from speaking; (as) mute as a fish . for example:讨论会上，大家都对提出的问题踊跃发表意见，而他却一直默不作声.

默不作声とよく使われでいる。沈黙という意味になります。