配电箱有总配电箱、分配电箱和开关箱三级设置,分配电箱与开关箱的距离一般不超过( )。
A.20m B.30mC.40m D.50m
参考答案:B
据报道,1995年,有人为了奖金自愿做超音速飞机的噪声作用试验,飞机从他们头顶掠过,尽管他们双手掩耳,还是全部被噪声击毙,而且死状十分难看.1994年,某国空军的喷气式飞机做超音速飞行试验,6个月后,地面农场的10000只鸡遭受噪声致死的有6000只,幸存下来的或脱毛或不下蛋,奶牛也挤不出牛奶.这一现象说明了什么?
He had hoped to tour the deserted temple for ____ fun but to his disappointment he didn’ t find ___ fun for doing that at all .
A./; /
B./; the
C.the; the
D.a; the