根据我国相关国标,有屏蔽层结构的软电缆,允许弯曲半径应不小于电缆外径的()倍。
A.4
B.6
C.10
D.12
参考答案:B
At the end of the race his legs ____ and he fell down on the ground.
A.gave out
B.gave off
C.worn out
D.used up
豪猪烯(hericenes),形状宛如伏地伸刺的动物,其键线式如右图。下列有关豪猪烯的说法正确的是
A.豪猪烯与乙烯互为同系物
B.豪猪烯分子中所有原子在同一平面
C.豪猪烯的分子式为:C14H20