如图,边长为1的正方形ABCD绕点A逆时针旋转45°后得到正方形AB1C1D1,边B1C1与CD交于点O,则四边形AB1OD 的周长是( )
A:22
B:3
C:2
D:1+2
Some students in this school abroad as exchange students every year.
辽宁号航空母舰满载时排水量达7万吨,它满载时所受的浮力为____ N,当舰载机起飞后,航空母舰所受浮力将 ____ (选填“不变”、“变小”或“变大”).( ρ水=1×l03kg/m3g取10N╱kg)
为打击德国共产党和进步人士,纳粹党制造了( )