紧抿嘴角
[jĭn mĭn zuĭ jiăo]
Means 'pursed lips', depicting the posture when one is trying to keep silent and not to talk more than he wants. Such an image implies seriousness, solemnity, or even holding back emotion rather than showing openly. Sometimes it may indicate dissatisfaction or resistance. In general, the idiom gives off a sense of being emotionally reserved.