胸骨左缘第2肋间有连续性震颤，提示
A．主动脉瓣狭窄B．主动脉瓣关闭不全C．肺动脉瓣狭窄D．动脉导管末闭E．二尖瓣狭窄
参考答案：D
传染病在某一地区流行后，人群感染状态的一般规律是
A．显性感染多
B．隐性感染多
C．潜在性感染多
D．健康带菌(病毒)者多
E．病后带菌(病毒)者多
Not only _____ help him with his maths , but you should help him with his Chinese. [ ]
A. you should
B. you will
C. should you
