M型超声心动图的二尖瓣水平波群可观察哪种结构的运动曲线()
A.主动脉瓣曲线
B. * * 肌曲线
C.主动脉根部曲线
D.肺动脉瓣曲线
E.二尖瓣前叶、后叶曲线
参考答案:E
—Can you go skateboarding with us, Toby?
—Sorry, I can't. I _____ take the piano lesson every Saturday morning.[ ]
A. can
B. can't
C. have to
CELL树