晶闸管对触发电路的要求。
参考答案:
1)触发脉冲具有足够的功率和一定的宽度2)触发脉冲与主电源电压必须同步3)触发脉冲的移向范围应满足变流装置提出的要求。
I still remember that terrible accident a few days ago, ____ more than 20 pupils were killed.
A.where
B.that
C.on which
D.which
脊髓受压的原因不包括()。
A.瘀血阻滞
B.组织水肿
C.脱位骨骼
D.骨折片
E.肌肉嵌入