1. My sister is a bad-tempered person who would snap at anybody whenever she feels like it.2. Whenever I bring a guy to my apartment my roommate always snaps at him and asks him to leave.3. My sister may sound harsh when she criticizes you for doing wrong things, but she means well.
 bad-tempered snap at somebody sound harsh很多時候我們說恰北北是表示兇的意思，snap at 是動詞，表示一個人說話語氣又急又兇的意思，是恰北北很貼切的翻譯。
My sister is ad-tempered and would snap at anybody whenever she feels like it.