风湿性心脏病中最易发生淬死的是
A．二尖瓣狭窄
B．二尖瓣关闭不全
C．主动脉瓣狭窄
D．主动脉瓣关闭不全
E．二尖瓣狭窄兼主动脉瓣关闭不全
参考答案：C
— Do you often ______ sports activities?
— Yes, what about you? [ ]
A. take part in
B. join
C. have
D. make
铁件主要测量炉柱曲度，炉体膨胀量，弹簧吨位和（）等。
A．拉条、炉框变化
B．拉条和保护面
C．拉条与炉墙
