三极管内部结构分为三个区，引出电极发射极的代号为()。
A
B
C
D. e
Which channel is designated for VHF Digital Selective Calling？
A. Channel 70
B. Channel 06
Channel 13
D. Channel 16
What is the minimum requirement of a GMDSS operator？
A. GMDSS operator license
B. Third officer license
C. General Radiotelephone Operator license and Radar Endorsement
D. General Radiotelephone license or First or Second Class Radiotelegraph license with GMDSS Radio Officer’s endorsement
以连续送进的焊丝做为电极和填充金属的焊接方法是()。
A. 焊条电弧焊
B. 熔化极气体保护焊
C. 鎢极氩弧焊
D. 等离子焊
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