嘴紧 meaning in English

tight-lipped; closemouthed; secretive

This is a secret , but i know i can count on your discretion
这可是个秘密，不过我知道你嘴紧（肯定不会告诉别人）。
He laid himself down and put his mouth close to this depression and called - " doodle - bug , doodle - bug , tell me what i want to know
他扑到地上，嘴紧贴着凹陷处喊道： “小甲虫，小甲虫，告诉我这究竟是怎么回事！
The check was sufficient . he resumed his retreat and descended . his air remained calm and cold , his small compressed mouth indexing his powers of self - control ; his face wearing still that terribly sterile expression which had spread thereon since her disclosure
他的神情既镇静又冷酷，他的小嘴紧紧闭着，说明他有自我控制的能力他的脸上仍然是一副令人感到可怕的神情，自从苔丝自我表白以来，他的脸上就有了那副神情。