He is even _____ than his brother. [ ]
A. funny
B. fun
C. funnier
D. more funny
答案:C
应急电源与电力网的正常电源之间( )采取防止并列运行的措施。
A.宜
B.应
C.必须
D.不可
造成舵机空舵的原因有哪些?