钨极氩弧焊采用的熄弧控制环节是有极衰减法。
参考答案:错
当飞机降落时,乘务员要求乘客咀嚼食物,其目的是使__________打开,可以使鼓膜内外的_________,防止鼓膜胀疼。
A RADIO SIGNAL FROM A DISTRESSED VESSEL AUTOMATICALLY DIRECTED TO A RCC GIVING POSITION,IDENTIFICATION,COURSE AND SPEED OF THE VESSEL AS WELL AS THE NATURE OF DISTRESS is known as().
A.Distress alert
B.Safety alert
C.Emergency alert
D.General alert