运动神经元病是一组病因为未明的选择性侵犯
A.锥体束
B.脊髓侧角细胞
C.脊髓前角细胞
D.皮质锥体细胞
E.脑干后组运动神经元
参考答案:A,C,D,E
We'd better go and tell her the _____ news. I'm sure she will be very _____ it. [ ]
A. surprising; surprised at
B. surprised; surprising to hear
C. interested; interesting in
D. interesting; interest in
交流接触器的栅片灭弧原理是由于触点上方的铁质栅片磁阻很小,电弧上部磁通大都进入(),使电弧周围空气中的磁场分布形式上疏下密,将电弧拉入灭弧栅。电弧被栅片分割多若干短弧,使起弧电压高于电源电压并产生阴极效应,栅片又大量吸收电弧的(),所以电弧被熄灭。