主动脉听诊区闻及收缩期喷射样杂音，向颈部传导，最可能的诊断是

A．二尖瓣狭窄
B．二尖瓣关闭不全
C．主动脉瓣狭窄
D．主动脉关闭不全
E．肺动脉瓣狭窄

7．Since you are here, you ____ as well stay here for long.

A．can

B．may

C．must

D．Should