切牙和尖牙间的裂隙为()
A.唇裂
B.颌裂
C.腭裂
D.横面裂
E.斜面裂
参考答案:B
I am told that the new law will come into _____ on January 1st next year.
A.effect
B.fashion
C.service
D.existence
晶闸管触发电路的触发脉冲要有一定的功率和宽度,这样才能保证晶闸管可靠导通。