风湿性心内膜炎常受侵犯的瓣膜是
A．二尖瓣
B．三尖瓣
C．主动脉瓣
D．肺动脉瓣
E．三尖瓣和肺动脉瓣
参考答案：A
Tomorrow is mother's birthday.
send her some flowers? [ ]
A. Let
B. Why don't
C. What about
D. why not
单一的中央银行制
