下列哪项不是肺栓塞的心电图表现（）
A.电轴右倾
B.肺性P波
C.快速房颤
D.ST段和T波改变
E.QT延长
参考答案：E
The two boys _____ late yesterday. [ ]
A. are all
B. are both
C. were all
D. were both
简要说明安全在铁路运输生产中的地位。
