We all feel it is Jack as well as his wife that 　　　　 for their son's bad performance at school.

A．are to blame　　

B．is to the blamed

C．are to be blamed

D．is to blame

稳定潜在型克山病，对诊断有意义的心电图改变是

A．T波低平

B．S-T段压低

C．Q-T间期延长

D．完全性右束支传导阻滞

E．S-T段抬高