二尖瓣狭窄最常见的原因是
A．风湿性心内膜炎
B．急性细菌性心内膜炎
C．动脉粥样硬化
D．亚急性细菌性心内膜炎
参考答案：A
当别人称赞你时, 你应该说: “____”。
A. Thanks. B. Good. C. Yes.
We will do everything we can to _____ him to stay, but if he wants to leave we won’t stand in his way.
A．convince
B．frighten
C．remind
D．confuse
