涡流检测线圈中次级绕组的主要作用是()。
A.在试样中感应出涡流
B.检出涡流的变化
C.在试样中感应出涡流和检出涡流的变化
D.提供直流磁饱和
参考答案:B
—If not controlled, some terrible diseases will spread in the stricken areas after the terrible earthquake.
—So people there are in _____ need of medical teams.
A.anxious
B.permanent
C.specific
D.desperate