SF6断路器中,SF6气体的作用是()。
A.绝缘
B.散热
C.绝缘和散热
D.灭弧、绝缘和散热
参考答案:D
2,11,32,71,134,( )。
A.137
B.187
C.227
D.247
If Mr. Brown _____ his sister to attend the party, she will certainly be glad to.
A.hopes
B.manages
C.demands
D.advises