板脸

例句：

1. 1. He always has a serious face when he talks to others.
   他和别人交谈时总是一脸严肃。
2. 2. Her face turned red with embarrassment.
   她的脸红了，因为尴尬。
3. 3. The teacher gave a stern look at the students.
   老师对学生严厉地看了一眼。