二尖瓣狭窄M型超声心动图示二尖瓣在收缩中、晚期向后移位，呈“吊床样”改变
参考答案：错
This is the best chance for you to go abroad. Don't ________.
A．throw it away
B．put it away
C．take it away
D．hide it away
瓦斯隧道各掘进工作面必须独立通风，严禁任何两个工作面之间（）通风。
