弯管弯曲部分的受拉侧中心线上下各()区域应进行磁粉或渗透检测,检测方法按JB4730.4-2005中的规定执行。
A.30°
B.45°
C.60°
参考答案:B
安全触板开关故障,可能导致电梯不关门现象()
Showing ______ to a current or former teacher is a fair reward and an act of gratitude that will also make you feel better.
A.appreciation
B.enjoyment
C.delight
D.pleasure