M型超声波检查显示二尖瓣前叶曲线双峰消失,呈城墙样改变,这是()
A.二尖瓣关闭不全
B.左房黏液瘤
C.先天性心脏病
D.二尖瓣狭窄
E.高血压性心脏病
参考答案:D
The Whites _____________ many places of interest since they came to China. [ ]
A. have visited
B. will visit
C. visited
D. visit
温度继电器KP52,检测油路的油温,当主变压器的油温超过()时,断开主断路器。
A、80℃
B、90℃
C、100℃
D、110℃