13. a condition caused by blocking the airways to the lungs (as with food or swelling of the larynx)
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14. a sudden unforeseen crisis (usually involving danger) that requires immediate action
15. an emergency procedure to help someone who is choking because food is lodged in the trachea
工作在放大状态的晶体管,流过发射结的主要是(),流过集电结的是()。
A.扩散电流
B.漂移电流
晶体管工作在放大区时,B-E间为, B-C间为;工作在饱和区时,B-E间为, B-C间为。
A. 正向偏置
B.反向偏置
C.零偏置
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