听课: 1.(听人讲课) attend a lecture; sit in on a class; listen to the teacher in class 短语和例子用心听课 listen to the teacher in class attentively2.(了解课堂教学) visit a class; visit classroom 短语和例子校长经常事先不通知地去听
聚精会神: concentrate one's attention (and energy) on; be absorbed; be all attention; concentrate one's mind on; direct one's energies to; gather one's wits; rivet [focus] one's attention on [upon];
