如图,正六边形ABCDEF内接于圆O,半径为4,则这个正六边形的边心距OM为____
海洋水族馆中,表演者需携带氧气瓶在水中与鱼“共舞”.氧气被压缩在钢瓶中,其原因正确的是( )
lán yāo
qīng xī
yǐn cáng
gǎn chù
____
mèi l
nǎo jīn
cuī cù
jiāo zào
Investigators have a____ enough evidence to put that thief in jail for many years.