S-2:seal someone's lips 不让某人说话
A:How about your exam?
A:你考试考得怎么样?
B:Sorry, I can't tell you.
B:抱歉我不能告诉你。
A:Why not? Are your lips sealed?
A:为什么?你的嘴被封住了吗?
B:No. Just because I failed in the exam.
B:不,只是因为我考得不好。