The point should be quite apparent by now: any sufficient source of DC curent may be used to turn the transistor on, and that source of current need only be a fraction of the amount of current needed to energize the lamp.
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举一反三
【单选题】From the fourth paragraph we learn that ______.
A.
heart attacks are more likely caused by alcohol than stroke
B.
moderate drinking discourage blood platelets from clotting
C.
boosting the levels of good cholesterol can lead to heart attacks
D.
moderate drinking protect people by making the blood cell clump