风湿性心瓣膜病
参考答案:
风湿热后所遗留下来的以心瓣膜病变为主的一种心脏病。
Mike often got into trouble with others at school,but his teacher didn't ___trying to help him . [ ]
A worry about
B afford to
C give up
D pay attention to
双倍频扫描的电视机电路中存储器读出的频率要比写入的频率高()。