threatening

The sky turned a threatening dark gray just before the massive thunderstorm hit the town.

(Chinese) 在大雷雨袭击小镇前，天空变成了阴森森的深灰色。

He was arrested for sending threatening emails to his former business partner.

(Chinese) 他因向以前的生意伙伴发送恐吓邮件而被捕。